chore: clean up decoder code

[muktihari]

• reset d.fileId to nil on releaseTemporaryObjects()
• fix typo profilType -> profileType
• remove (*Decoder) log as it simply a fmt.Fprintf.
• check d.option.logWriter == nil before try printing the log to avoid unnecessary allocation when d.option.logWriter is nil.
• simplify other codes.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (6bf188f) to head (c9d3845).

Additional details and impacted files

@@            Coverage Diff            @@
##            master      #491   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           42        42           
  Lines         3859      3860    +1     
=========================================
+ Hits          3859      3860    +1     

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