Improve vessel sources error handling (#121)

* Improve 'vessel sources' error handling

* 0.6.1

package.json

@@ -2,7 +2,7 @@
     "name": "vscode-motoko",
     "displayName": "Motoko",
     "description": "Motoko language support",
-    "version": "0.6.0",
+    "version": "0.6.1",
     "publisher": "dfinity-foundation",
     "repository": "https://github.com/dfinity/vscode-motoko",
     "engines": {

src/server/server.ts

@@ -57,28 +57,28 @@ const ignoreGlobs = [
 ];
 
 function getVesselSources(directory: string): [string, string][] {
-    if (!existsSync('vessel')) {
-        // Fallback Vessel functionality
-        return vesselSources(directory);
-    }
-
-    const flags = execSync('vessel sources', {
-        cwd: directory,
-    }).toString('utf8');
-    const args = flags.split(' ');
-    const sources: [string, string][] = [];
-    let nextArg;
-    while ((nextArg = args.shift())) {
-        if (nextArg === '--package') {
-            const name = args.shift()!;
-            const relativePath = args.shift();
-            if (!relativePath) {
-                continue;
+    try {
+        const flags = execSync('vessel sources', {
+            cwd: directory,
+        }).toString('utf8');
+        const args = flags.split(' ');
+        const sources: [string, string][] = [];
+        let nextArg;
+        while ((nextArg = args.shift())) {
+            if (nextArg === '--package') {
+                const name = args.shift()!;
+                const relativePath = args.shift();
+                if (!relativePath) {
+                    continue;
+                }
+                sources.push([name, relativePath]);
             }
-            sources.push([name, relativePath]);
         }
+        return sources;
+    } catch (err) {
+        console.error('Error while running `vessel sources`:', err);
+        return vesselSources(directory);
     }
-    return sources;
 }
 
 let vesselChangeTimeout: ReturnType<typeof setTimeout>;