diff --git a/LrcParser.Tests/Parser/Lrc/Lines/LrcLyricParserTest.cs b/LrcParser.Tests/Parser/Lrc/Lines/LrcLyricParserTest.cs
index cc4b6b2..ce74d18 100644
--- a/LrcParser.Tests/Parser/Lrc/Lines/LrcLyricParserTest.cs
+++ b/LrcParser.Tests/Parser/Lrc/Lines/LrcLyricParserTest.cs
@@ -33,7 +33,7 @@ public void TestDecode(string lyric, string text, string[] timeTags)
         var expected = new LrcLyric
         {
             Text = text,
-            TimeTags = TestCaseTagHelper.ParseTimeTags(timeTags)
+            TimeTags = TestCaseTagHelper.ParseTimeTags(timeTags),
         };
         var actual = Decode(lyric);
 
@@ -51,7 +51,7 @@ public void TestEncode(string text, string[] timeTags, string expected)
         var lyric = new LrcLyric
         {
             Text = text,
-            TimeTags = TestCaseTagHelper.ParseTimeTags(timeTags)
+            TimeTags = TestCaseTagHelper.ParseTimeTags(timeTags),
         };
         var actual = Encode(lyric);
 
diff --git a/LrcParser.Tests/Parser/Lrc/Lines/LrcRubyParserTest.cs b/LrcParser.Tests/Parser/Lrc/Lines/LrcRubyParserTest.cs
index 8b56263..201975d 100644
--- a/LrcParser.Tests/Parser/Lrc/Lines/LrcRubyParserTest.cs
+++ b/LrcParser.Tests/Parser/Lrc/Lines/LrcRubyParserTest.cs
@@ -35,7 +35,7 @@ public void TestDecode(string rubyTag, string parent, string ruby, string[] time
             Ruby = ruby,
             TimeTags = TestCaseTagHelper.ParseTimeTags(timeTags),
             StartTime = startTime,
-            EndTime = endTime
+            EndTime = endTime,
         };
         var actual = Decode(rubyTag);
 
@@ -59,7 +59,7 @@ public void TestEncode(string parent, string ruby, string[] timeTags, int? start
             Ruby = ruby,
             TimeTags = TestCaseTagHelper.ParseTimeTags(timeTags),
             StartTime = startTime,
-            EndTime = endTime
+            EndTime = endTime,
         };
         var actual = Encode(rubyTag);
 
diff --git a/LrcParser.Tests/Parser/Lrc/LrcParserTest.cs b/LrcParser.Tests/Parser/Lrc/LrcParserTest.cs
index 70f0d24..bf11e37 100644
--- a/LrcParser.Tests/Parser/Lrc/LrcParserTest.cs
+++ b/LrcParser.Tests/Parser/Lrc/LrcParserTest.cs
@@ -14,7 +14,7 @@ public void TestDecode()
     {
         var lrcText = new[]
         {
-            "[00:17:97]帰[00:18:37]り[00:18:55]道[00:18:94]は[00:19:22]"
+            "[00:17:97]帰[00:18:37]り[00:18:55]道[00:18:94]は[00:19:22]",
         };
 
         var song = new Song
@@ -31,9 +31,9 @@ public void TestDecode()
                         { new TextIndex(2), 18550 },
                         { new TextIndex(3), 18940 },
                         { new TextIndex(3, IndexState.End), 19220 },
-                    }
-                }
-            }
+                    },
+                },
+            },
         };
 
         checkDecode(lrcText, song);
@@ -47,7 +47,7 @@ public void TestDecodeWithRuby()
             "[00:01:00]島[00:02:00]島[00:03:00]島[00:04:00]",
             "@Ruby1=島,しま,,[00:02:00]",
             "@Ruby2=島,じま,[00:02:00],[00:03:00]",
-            "@Ruby3=島,とう,[00:03:00]"
+            "@Ruby3=島,とう,[00:03:00]",
         };
 
         var song = new Song
@@ -70,23 +70,23 @@ public void TestDecodeWithRuby()
                         {
                             Text = "しま",
                             StartCharIndex = 0,
-                            EndCharIndex = 0
+                            EndCharIndex = 0,
                         },
                         new()
                         {
                             Text = "じま",
                             StartCharIndex = 1,
-                            EndCharIndex = 1
+                            EndCharIndex = 1,
                         },
                         new()
                         {
                             Text = "とう",
                             StartCharIndex = 2,
-                            EndCharIndex = 2
-                        }
-                    }
+                            EndCharIndex = 2,
+                        },
+                    },
                 },
-            }
+            },
         };
 
         checkDecode(lrcText, song);
@@ -100,7 +100,7 @@ public void TestDecodeWithRubyAndRubyTimeTag()
             "[00:01:00]島[00:02:00]島[00:03:00]島[00:04:00]",
             "@Ruby1=島,し[00:00:50]ま,,[00:02:00]",
             "@Ruby2=島,じ[00:00:50]ま,[00:02:00],[00:03:00]",
-            "@Ruby3=島,と[00:00:50]う,[00:03:00]"
+            "@Ruby3=島,と[00:00:50]う,[00:03:00]",
         };
 
         var song = new Song
@@ -124,34 +124,34 @@ public void TestDecodeWithRubyAndRubyTimeTag()
                             Text = "しま",
                             TimeTags = new SortedDictionary<TextIndex, int?>
                             {
-                                { new TextIndex(1), 1500 }
+                                { new TextIndex(1), 1500 },
                             },
                             StartCharIndex = 0,
-                            EndCharIndex = 0
+                            EndCharIndex = 0,
                         },
                         new()
                         {
                             Text = "じま",
                             TimeTags = new SortedDictionary<TextIndex, int?>
                             {
-                                { new TextIndex(1), 2500 }
+                                { new TextIndex(1), 2500 },
                             },
                             StartCharIndex = 1,
-                            EndCharIndex = 1
+                            EndCharIndex = 1,
                         },
                         new()
                         {
                             Text = "とう",
                             TimeTags = new SortedDictionary<TextIndex, int?>
                             {
-                                { new TextIndex(1), 3500 }
+                                { new TextIndex(1), 3500 },
                             },
                             StartCharIndex = 2,
-                            EndCharIndex = 2
-                        }
-                    }
+                            EndCharIndex = 2,
+                        },
+                    },
                 },
-            }
+            },
         };
 
         checkDecode(lrcText, song);
@@ -165,7 +165,7 @@ public void TestDecodeWithSameRubyWithDifferentRubyTimeTag()
             "[00:01:00]島[00:02:00]島[00:03:00]島[00:04:00]",
             "@Ruby1=島,し[00:00:40]ま,,[00:02:00]",
             "@Ruby2=島,し[00:00:50]ま,[00:02:00],[00:03:00]",
-            "@Ruby3=島,し[00:00:60]ま,[00:03:00]"
+            "@Ruby3=島,し[00:00:60]ま,[00:03:00]",
         };
 
         var song = new Song
@@ -189,34 +189,34 @@ public void TestDecodeWithSameRubyWithDifferentRubyTimeTag()
                             Text = "しま",
                             TimeTags = new SortedDictionary<TextIndex, int?>
                             {
-                                { new TextIndex(1), 1400 }
+                                { new TextIndex(1), 1400 },
                             },
                             StartCharIndex = 0,
-                            EndCharIndex = 0
+                            EndCharIndex = 0,
                         },
                         new()
                         {
                             Text = "しま",
                             TimeTags = new SortedDictionary<TextIndex, int?>
                             {
-                                { new TextIndex(1), 2500 }
+                                { new TextIndex(1), 2500 },
                             },
                             StartCharIndex = 1,
-                            EndCharIndex = 1
+                            EndCharIndex = 1,
                         },
                         new()
                         {
                             Text = "しま",
                             TimeTags = new SortedDictionary<TextIndex, int?>
                             {
-                                { new TextIndex(1), 3600 }
+                                { new TextIndex(1), 3600 },
                             },
                             StartCharIndex = 2,
-                            EndCharIndex = 2
-                        }
-                    }
+                            EndCharIndex = 2,
+                        },
+                    },
                 },
-            }
+            },
         };
 
         checkDecode(lrcText, song);
@@ -231,7 +231,7 @@ public void TestDecodeWithNoTimeRangeRuby()
             "@Ruby1=カ,か",
             "@Ruby2=ラ,ら",
             "@Ruby3=オ,お",
-            "@Ruby4=ケ,け"
+            "@Ruby4=ケ,け",
         };
 
         var song = new Song
@@ -247,29 +247,29 @@ public void TestDecodeWithNoTimeRangeRuby()
                         {
                             Text = "か",
                             StartCharIndex = 0,
-                            EndCharIndex = 0
+                            EndCharIndex = 0,
                         },
                         new()
                         {
                             Text = "ら",
                             StartCharIndex = 1,
-                            EndCharIndex = 1
+                            EndCharIndex = 1,
                         },
                         new()
                         {
                             Text = "お",
                             StartCharIndex = 2,
-                            EndCharIndex = 2
+                            EndCharIndex = 2,
                         },
                         new()
                         {
                             Text = "け",
                             StartCharIndex = 3,
-                            EndCharIndex = 3
-                        }
-                    }
+                            EndCharIndex = 3,
+                        },
+                    },
                 },
-            }
+            },
         };
 
         checkDecode(lrcText, song);
@@ -285,7 +285,7 @@ public void TestDecodeWithRubyInDifferentLine()
             "[00:05:00]島[00:06:00]",
             "@Ruby1=島,しま,,[00:02:00]",
             "@Ruby2=島,じま,[00:03:00],[00:04:00]",
-            "@Ruby3=島,とう,[00:05:00]"
+            "@Ruby3=島,とう,[00:05:00]",
         };
 
         var song = new Song
@@ -306,9 +306,9 @@ public void TestDecodeWithRubyInDifferentLine()
                         {
                             Text = "しま",
                             StartCharIndex = 0,
-                            EndCharIndex = 0
-                        }
-                    }
+                            EndCharIndex = 0,
+                        },
+                    },
                 },
                 new()
                 {
@@ -324,9 +324,9 @@ public void TestDecodeWithRubyInDifferentLine()
                         {
                             Text = "じま",
                             StartCharIndex = 0,
-                            EndCharIndex = 0
-                        }
-                    }
+                            EndCharIndex = 0,
+                        },
+                    },
                 },
                 new()
                 {
@@ -342,11 +342,11 @@ public void TestDecodeWithRubyInDifferentLine()
                         {
                             Text = "とう",
                             StartCharIndex = 0,
-                            EndCharIndex = 0
-                        }
-                    }
-                }
-            }
+                            EndCharIndex = 0,
+                        },
+                    },
+                },
+            },
         };
 
         checkDecode(lrcText, song);
@@ -359,7 +359,7 @@ public void TestDecodeWithInvalid()
         var lrcText = new[]
         {
             "[00:01:00]島[00:02:00]",
-            "@Ruby1=島,島"
+            "@Ruby1=島,島",
         };
 
         var song = new Song
@@ -375,7 +375,7 @@ public void TestDecodeWithInvalid()
                         { new TextIndex(0, IndexState.End), 2000 },
                     },
                 },
-            }
+            },
         };
 
         checkDecode(lrcText, song);
@@ -398,14 +398,14 @@ public void TestEncode()
                         { new TextIndex(2), 18550 },
                         { new TextIndex(3), 18940 },
                         { new TextIndex(3, IndexState.End), 19220 },
-                    }
-                }
-            }
+                    },
+                },
+            },
         };
 
         var lrcText = new[]
         {
-            "[00:17.97]帰[00:18.37]り[00:18.55]道[00:18.94]は[00:19.22]"
+            "[00:17.97]帰[00:18.37]り[00:18.55]道[00:18.94]は[00:19.22]",
         };
 
         checkEncode(song, lrcText);
@@ -434,23 +434,23 @@ public void TestEncodeWithRuby()
                         {
                             Text = "しま",
                             StartCharIndex = 0,
-                            EndCharIndex = 0
+                            EndCharIndex = 0,
                         },
                         new()
                         {
                             Text = "じま",
                             StartCharIndex = 1,
-                            EndCharIndex = 1
+                            EndCharIndex = 1,
                         },
                         new()
                         {
                             Text = "とう",
                             StartCharIndex = 2,
-                            EndCharIndex = 2
-                        }
-                    }
+                            EndCharIndex = 2,
+                        },
+                    },
                 },
-            }
+            },
         };
 
         var lrcText = new[]
@@ -459,7 +459,7 @@ public void TestEncodeWithRuby()
             "",
             "@Ruby1=島,しま,,[00:02.00]",
             "@Ruby2=島,じま,[00:02.00],[00:03.00]",
-            "@Ruby3=島,とう,[00:03.00]"
+            "@Ruby3=島,とう,[00:03.00]",
         };
 
         checkEncode(song, lrcText);
@@ -489,34 +489,34 @@ public void TestEncodeWithRubyAndRubyTimeTag()
                             Text = "しま",
                             TimeTags = new SortedDictionary<TextIndex, int?>
                             {
-                                { new TextIndex(1), 1500 }
+                                { new TextIndex(1), 1500 },
                             },
                             StartCharIndex = 0,
-                            EndCharIndex = 0
+                            EndCharIndex = 0,
                         },
                         new()
                         {
                             Text = "じま",
                             TimeTags = new SortedDictionary<TextIndex, int?>
                             {
-                                { new TextIndex(1), 2500 }
+                                { new TextIndex(1), 2500 },
                             },
                             StartCharIndex = 1,
-                            EndCharIndex = 1
+                            EndCharIndex = 1,
                         },
                         new()
                         {
                             Text = "とう",
                             TimeTags = new SortedDictionary<TextIndex, int?>
                             {
-                                { new TextIndex(1), 3500 }
+                                { new TextIndex(1), 3500 },
                             },
                             StartCharIndex = 2,
-                            EndCharIndex = 2
-                        }
-                    }
+                            EndCharIndex = 2,
+                        },
+                    },
                 },
-            }
+            },
         };
 
         var lrcText = new[]
@@ -525,7 +525,7 @@ public void TestEncodeWithRubyAndRubyTimeTag()
             "",
             "@Ruby1=島,し[00:00.50]ま,,[00:02.00]",
             "@Ruby2=島,じ[00:00.50]ま,[00:02.00],[00:03.00]",
-            "@Ruby3=島,と[00:00.50]う,[00:03.00]"
+            "@Ruby3=島,と[00:00.50]う,[00:03.00]",
         };
 
         checkEncode(song, lrcText);
@@ -556,20 +556,20 @@ public void TestEncodeWithSameRubyWithDifferentRubyTimeTag()
                             Text = "しま",
                             TimeTags = new SortedDictionary<TextIndex, int?>
                             {
-                                { new TextIndex(1), 1400 }
+                                { new TextIndex(1), 1400 },
                             },
                             StartCharIndex = 0,
-                            EndCharIndex = 0
+                            EndCharIndex = 0,
                         },
                         new()
                         {
                             Text = "しま",
                             TimeTags = new SortedDictionary<TextIndex, int?>
                             {
-                                { new TextIndex(1), 2500 }
+                                { new TextIndex(1), 2500 },
                             },
                             StartCharIndex = 1,
-                            EndCharIndex = 1
+                            EndCharIndex = 1,
                         },
                         new()
                         {
@@ -577,10 +577,10 @@ public void TestEncodeWithSameRubyWithDifferentRubyTimeTag()
                             TimeTags = new SortedDictionary<TextIndex, int?>
                             {
                                 // will merge with second time-tag
-                                { new TextIndex(1), 3500 }
+                                { new TextIndex(1), 3500 },
                             },
                             StartCharIndex = 2,
-                            EndCharIndex = 2
+                            EndCharIndex = 2,
                         },
                         new()
                         {
@@ -588,14 +588,14 @@ public void TestEncodeWithSameRubyWithDifferentRubyTimeTag()
                             TimeTags = new SortedDictionary<TextIndex, int?>
                             {
                                 // although the relative time is same as the first time-tag, but might not be able to merge.
-                                { new TextIndex(1), 4400 }
+                                { new TextIndex(1), 4400 },
                             },
                             StartCharIndex = 3,
-                            EndCharIndex = 3
-                        }
-                    }
+                            EndCharIndex = 3,
+                        },
+                    },
                 },
-            }
+            },
         };
 
         var lrcText = new[]
@@ -626,29 +626,29 @@ public void TestEncodeWithNoTimeRangeRuby()
                         {
                             Text = "か",
                             StartCharIndex = 0,
-                            EndCharIndex = 0
+                            EndCharIndex = 0,
                         },
                         new()
                         {
                             Text = "ら",
                             StartCharIndex = 1,
-                            EndCharIndex = 1
+                            EndCharIndex = 1,
                         },
                         new()
                         {
                             Text = "お",
                             StartCharIndex = 2,
-                            EndCharIndex = 2
+                            EndCharIndex = 2,
                         },
                         new()
                         {
                             Text = "け",
                             StartCharIndex = 3,
-                            EndCharIndex = 3
-                        }
-                    }
+                            EndCharIndex = 3,
+                        },
+                    },
                 },
-            }
+            },
         };
 
         var lrcText = new[]
@@ -658,7 +658,7 @@ public void TestEncodeWithNoTimeRangeRuby()
             "@Ruby1=カ,か",
             "@Ruby2=ラ,ら",
             "@Ruby3=オ,お",
-            "@Ruby4=ケ,け"
+            "@Ruby4=ケ,け",
         };
 
         checkEncode(song, lrcText);
@@ -685,9 +685,9 @@ public void TestEncodeWithRubyInDifferentLine()
                         {
                             Text = "しま",
                             StartCharIndex = 0,
-                            EndCharIndex = 0
-                        }
-                    }
+                            EndCharIndex = 0,
+                        },
+                    },
                 },
                 new()
                 {
@@ -703,9 +703,9 @@ public void TestEncodeWithRubyInDifferentLine()
                         {
                             Text = "じま",
                             StartCharIndex = 0,
-                            EndCharIndex = 0
-                        }
-                    }
+                            EndCharIndex = 0,
+                        },
+                    },
                 },
                 new()
                 {
@@ -721,11 +721,11 @@ public void TestEncodeWithRubyInDifferentLine()
                         {
                             Text = "とう",
                             StartCharIndex = 0,
-                            EndCharIndex = 0
-                        }
-                    }
-                }
-            }
+                            EndCharIndex = 0,
+                        },
+                    },
+                },
+            },
         };
 
         var lrcText = new[]
@@ -734,7 +734,7 @@ public void TestEncodeWithRubyInDifferentLine()
             "",
             "@Ruby1=島,しま,,[00:02.00]",
             "@Ruby2=島,じま,[00:03.00],[00:04.00]",
-            "@Ruby3=島,とう,[00:05.00]"
+            "@Ruby3=島,とう,[00:05.00]",
         };
 
         checkEncode(song, lrcText);
@@ -747,7 +747,7 @@ public void TestEncodeWithEmptyFile()
 
         var lrcText = new[]
         {
-            ""
+            "",
         };
 
         checkEncode(song, lrcText);
diff --git a/LrcParser.Tests/Parser/Lrc/Utils/LrcTimedTextUtilsTest.cs b/LrcParser.Tests/Parser/Lrc/Utils/LrcTimedTextUtilsTest.cs
index 6111bc3..8b26b74 100644
--- a/LrcParser.Tests/Parser/Lrc/Utils/LrcTimedTextUtilsTest.cs
+++ b/LrcParser.Tests/Parser/Lrc/Utils/LrcTimedTextUtilsTest.cs
@@ -15,7 +15,7 @@ public class LrcTimedTextUtilsTest
     [TestCase("[00:17:97]帰[00:18:37]り[00:18:55]道[00:18:94]は[00:19:22] ", "帰り道は ", new[] { "[0,start]:17970", "[1,start]:18370", "[2,start]:18550", "[3,start]:18940", "[3,end]:19220" })]
     [TestCase("帰[00:18:37]り[00:18:55]道[00:18:94]は[00:19:22]", "帰り道は", new[] { "[1,start]:18370", "[2,start]:18550", "[3,start]:18940", "[3,end]:19220" })]
     [TestCase("[00:17:97]帰[00:18:37]り[00:18:55]道[00:18:94]は", "帰り道は", new[] { "[0,start]:17970", "[1,start]:18370", "[2,start]:18550", "[3,start]:18940" })]
-    [TestCase("[00:51.00][01:29.99][01:48.29][02:31.00][02:41.99]You gotta fight !", "You gotta fight !", new string[] { "[0,start]:51000" })] // decode with invalid format.
+    [TestCase("[00:51.00][01:29.99][01:48.29][02:31.00][02:41.99]You gotta fight !", "You gotta fight !", new[] { "[0,start]:51000" })] // decode with invalid format.
     [TestCase("帰り道は", "帰り道は", new string[] { })]
     [TestCase("", "", new string[] { })]
     [TestCase(null, "", new string[] { })]
diff --git a/LrcParser.Tests/Parser/LyricParserTest.cs b/LrcParser.Tests/Parser/LyricParserTest.cs
index 050af22..d054498 100644
--- a/LrcParser.Tests/Parser/LyricParserTest.cs
+++ b/LrcParser.Tests/Parser/LyricParserTest.cs
@@ -52,7 +52,7 @@ protected override Song PostProcess(List<object> values)
                 Lyrics = lines.Select(l => new Lyric
                 {
                     Text = l,
-                }).ToList()
+                }).ToList(),
             };
         }
 
diff --git a/LrcParser/Extension/EnumerableExtensions.cs b/LrcParser/Extension/EnumerableExtensions.cs
index 1cf406c..4fbec24 100644
--- a/LrcParser/Extension/EnumerableExtensions.cs
+++ b/LrcParser/Extension/EnumerableExtensions.cs
@@ -42,6 +42,8 @@ public static IEnumerable<IGrouping<TKey, TSource>> GroupByContinuous<TSource, T
             list.Clear();
         }
 
+        yield break;
+
         static bool equal(TKey? key1, TKey? key2)
         {
             if (key1 == null)
diff --git a/LrcParser/Model/TextIndex.cs b/LrcParser/Model/TextIndex.cs
index c4cf03d..58bd2d5 100644
--- a/LrcParser/Model/TextIndex.cs
+++ b/LrcParser/Model/TextIndex.cs
@@ -37,7 +37,7 @@ public bool Equals(TextIndex other)
         return Index == other.Index && State == other.State;
     }
 
-    public override bool Equals(object obj)
+    public override bool Equals(object? obj)
     {
         if (obj is TextIndex textIndex)
             return Equals(textIndex);
@@ -73,5 +73,5 @@ public enum IndexState
 {
     Start = 0,
 
-    End = 1
+    End = 1,
 }
diff --git a/LrcParser/Parser/Lrc/Lines/LrcLyricParser.cs b/LrcParser/Parser/Lrc/Lines/LrcLyricParser.cs
index 195f8cc..62ded31 100644
--- a/LrcParser/Parser/Lrc/Lines/LrcLyricParser.cs
+++ b/LrcParser/Parser/Lrc/Lines/LrcLyricParser.cs
@@ -18,7 +18,7 @@ public override LrcLyric Decode(string text)
         return new LrcLyric
         {
             Text = lyric,
-            TimeTags = timeTags
+            TimeTags = timeTags,
         };
     }
 
diff --git a/LrcParser/Parser/Lrc/Lines/LrcRubyParser.cs b/LrcParser/Parser/Lrc/Lines/LrcRubyParser.cs
index 8308bcc..53ef629 100644
--- a/LrcParser/Parser/Lrc/Lines/LrcRubyParser.cs
+++ b/LrcParser/Parser/Lrc/Lines/LrcRubyParser.cs
@@ -45,7 +45,7 @@ public override string Encode(LrcRuby component, int index)
 
         var input = $"@Ruby{index + 1}={parent},{ruby},{startTime},{endTime}";
 
-        const string remove_last_comma_pattern = @"([,]*)$";
+        const string remove_last_comma_pattern = "([,]*)$";
         return Regex.Replace(input, remove_last_comma_pattern, "");
     }
 }
diff --git a/LrcParser/Parser/Lrc/LrcParser.cs b/LrcParser/Parser/Lrc/LrcParser.cs
index b8001a5..5d384a6 100644
--- a/LrcParser/Parser/Lrc/LrcParser.cs
+++ b/LrcParser/Parser/Lrc/LrcParser.cs
@@ -31,8 +31,8 @@ protected override Song PostProcess(List<object> values)
             {
                 Text = l.Text,
                 TimeTags = getTimeTags(l.TimeTags),
-                RubyTags = getRubyTags(rubies, l).ToList()
-            }).ToList()
+                RubyTags = getRubyTags(rubies, l).ToList(),
+            }).ToList(),
         };
 
         static IEnumerable<RubyTag> getRubyTags(IEnumerable<LrcRuby> rubyTags, LrcLyric lyric)
@@ -68,7 +68,7 @@ static IEnumerable<RubyTag> getRubyTags(IEnumerable<LrcRuby> rubyTags, LrcLyric
                             Text = rubyTag.Ruby,
                             TimeTags = getTimeTags(rubyTag.TimeTags, startTimeTag.Value),
                             StartCharIndex = startLyricCharIndex,
-                            EndCharIndex = endLyricCharIndex
+                            EndCharIndex = endLyricCharIndex,
                         };
                     }
                     else
@@ -85,7 +85,7 @@ static IEnumerable<RubyTag> getRubyTags(IEnumerable<LrcRuby> rubyTags, LrcLyric
                             Text = rubyTag.Ruby,
                             TimeTags = getTimeTags(rubyTag.TimeTags, startTimeTag.Value),
                             StartCharIndex = convertStartTextIndexToCharIndex(startTimeTag.Key),
-                            EndCharIndex = convertEndTextIndexToCharIndex(endTimeTag.Key)
+                            EndCharIndex = convertEndTextIndexToCharIndex(endTimeTag.Key),
                         };
                     }
                 }
@@ -102,7 +102,7 @@ static int convertEndTextIndexToCharIndex(TextIndex textIndex) =>
             {
                 IndexState.Start => textIndex.Index - 1,
                 IndexState.End => textIndex.Index,
-                _ => throw new ArgumentOutOfRangeException()
+                _ => throw new ArgumentOutOfRangeException(),
             };
     }
 
@@ -136,7 +136,7 @@ protected override IEnumerable<object> PreProcess(Song song)
                                      .GroupByContinuous(x => new RubyGroup
                                      {
                                          Ruby = x.Ruby,
-                                         TimeTags = x.TimeTags
+                                         TimeTags = x.TimeTags,
                                      }).ToList();
 
             // then, combine those continuous ruby.
@@ -159,11 +159,13 @@ protected override IEnumerable<object> PreProcess(Song song)
                     Parent = parent,
                     TimeTags = timeTags,
                     StartTime = minStartTime,
-                    EndTime = maxEndTime
+                    EndTime = maxEndTime,
                 };
             }
         }
 
+        yield break;
+
         static IEnumerable<LrcRuby> getRubyTags(Lyric lyric)
         {
             var timeTags = lyric.TimeTags;
diff --git a/LrcParser/Parser/Lrc/Utils/TimeTagUtils.cs b/LrcParser/Parser/Lrc/Utils/TimeTagUtils.cs
index 7944474..e9d801b 100644
--- a/LrcParser/Parser/Lrc/Utils/TimeTagUtils.cs
+++ b/LrcParser/Parser/Lrc/Utils/TimeTagUtils.cs
@@ -36,6 +36,7 @@ internal static int TimeTagToMillionSecond(string timeTag)
     {
         if (timeTag.Length < 10 || timeTag[0] != '[' || !char.IsDigit(timeTag[1]))
             return -1;
+
         int minute = int.Parse(timeTag.Substring(1, 2));
         int second = int.Parse(timeTag.Substring(4, 2));
         int millionSecond = int.Parse(timeTag.Substring(7, 2));
diff --git a/LrcParser/Utils/TextIndexUtils.cs b/LrcParser/Utils/TextIndexUtils.cs
index 57530d5..a8e130e 100644
--- a/LrcParser/Utils/TextIndexUtils.cs
+++ b/LrcParser/Utils/TextIndexUtils.cs
@@ -42,6 +42,6 @@ internal static T GetValueByState<T>(TextIndex index, T startValue, T endValue)
         {
             IndexState.Start => startValue,
             IndexState.End => endValue,
-            _ => throw new ArgumentOutOfRangeException(nameof(index))
+            _ => throw new ArgumentOutOfRangeException(nameof(index)),
         };
 }