1:many sourcemaps - Cannot read property 'source' of undefined

[tomardern]

Hi,

I'm getting a Cannot read property 'source' of undefined error when trying to process a file compressed.min.js which has the following compressed.js.map. All the sources are in the same directory.

{
  "version": 3,
  "file": "compressed.min.js",
  "sources": [
    "widget.js",
    "plugin.js",
    "app.js"
  ],
  "names": [
    "Widget",
    "console",
    "log",
    "Plugin",
    "window",
    "onload"
  ],
  "sourceRoot": "/project/",
  "mappings": "AAAA,GAAIA,QAAS,WAGX,GAAIA,GAAS,WACXC,QAAQC,IAAI,yBAId,OAAOF,MCRLG,OAAS,WAGX,GAAIA,GAAS,WACXF,QAAQC,IAAI,yBAId,OAAOC,KCRTC,QAAOC,OAAS,WACfJ,QAAQC,IAAI,wCAEC,IAAIF,QAEJ,GAAIG"
}

Full Error below:

(node:79066) UnhandledPromiseRejectionWarning: TypeError: Cannot read property 'source' of undefined
    at V8ToIstanbul._maybeRemapStartColEndCol (/project/node_modules/v8-to-istanbul/lib/v8-to-istanbul.js:188:40)
    at /project/node_modules/v8-to-istanbul/lib/v8-to-istanbul.js:110:60
    at Array.forEach (<anonymous>)
    at /project/node_modules/v8-to-istanbul/lib/v8-to-istanbul.js:109:20
    at Array.forEach (<anonymous>)
    at V8ToIstanbul.applyCoverage (/project/node_modules/v8-to-istanbul/lib/v8-to-istanbul.js:108:12)

However, if I include the "sourcesContent", for example:

{
  "version": 3,
  "file": "compressed.min.js",
  "sources": [
    "widget.js",
    "plugin.js",
    "app.js"
  ],
  "names": [
    "Widget",
    "console",
    "log",
    "Plugin",
    "window",
    "onload"
  ],
  "sourcesContent": [
    "var Widget = (function () {\n  // Constructor\n  var Widget = function () {\n    console.log(\"Logged from widget.js\");\n  };\n\n  // Export Widget.\n  return Widget;\n})();",
    "var Plugin = (function () {\n  // Constructor\n  var Plugin = function () {\n    console.log(\"Logged from plugin.js\");\n  };\n\n  // Export Plugin.\n  return Plugin;\n})();",
    "window.onload = function () {\n  console.log(\"This was logged from the app.js file.\");\n\n  var widget = new Widget();\n\n  var plugin = new Plugin();\n};"
  ],
  "mappings": "AAAA,GAAIA,QAAS,WAGX,GAAIA,GAAS,WACXC,QAAQC,IAAI,yBAId,OAAOF,MCRLG,OAAS,WAGX,GAAIA,GAAS,WACXF,QAAQC,IAAI,yBAId,OAAOC,KCRTC,QAAOC,OAAS,WACfJ,QAAQC,IAAI,wCAEC,IAAIF,QAEJ,GAAIG"
}

Then the instanbul report is generated successfully.

---

The following also works:

const map = JSON.parse(fs.readFileSync("compressed.js.map"));
map.sourcesContent = map.sources.map((f) =>fs.readFileSync(f, "utf-8"));

const converter = v8toIstanbul("compressed.min.js", undefined, {
  sourceMap: { sourcemap: map },
});
return converter.load().then((c) => {
  converter.applyCoverage(v8Coverage);
  console.info(JSON.stringify(converter.toIstanbul()));
});

---

After some debugging:

If I change the following line (https://github.com/istanbuljs/v8-to-istanbul/blob/master/lib/v8-to-istanbul.js#L51)

...
 if (this.rawSourceMap.sourcemap.sources.length > 1) {
        this.sourceMap = await new SourceMapConsumer(this.rawSourceMap.sourcemap)
   ...

to false, so that it fetches the files from disk, then it all seems ok :)

...
if (false) {
       this.sourceMap = await new SourceMapConsumer(this.rawSourceMap.sourcemap)
  ...

Potentially the this.rawSourceMap.sourcemap.sources.length > 1 should also check that sourcesContent is defined for each of the sources?

Thanks!