The Broccoli Plugin: [UglifyWriter] failed with

Question

I've had this error for 2 weeks now while trying to build an ember app in production. Building it in dev environment works fine. I also realized that disabling minifyJs in ember-cli-build prevents the error but then, the app gets stuck at loading in the browser, and in the console, I see another error: "could not import ember-resolver". My guess is that this is as a result of the UglifyWriter not understanding some code somewhere. The full error is: Build failed. File: assets/vendor.js (95443:4) The Broccoli Plugin: [UglifyWriter] failed with: Error at new JS_Parse_Error (eval at (/home/larisoft/frontend/node_modules/uglify-js/tools/node.js:1:1), :1545:18) ``` at js_error (eval at (/home/larisoft/frontend/node_modules/uglify-js/tools/node.js:1:1), :1553:11) at croak (eval at (/home/larisoft/frontend/node_modules/uglify-js/tools/node.js:1:1), :2092:9) at token_error (eval at (/home/larisoft/frontend/node_modules/uglify-js/tools/…

Accepted Answer

It seems like uglify.js has some problems with ES6 files: https://forum.ionicframework.com/t/uglifyjs-fails-with-js-parse-error-error-but-no-stack-trace/66094. In my case it was enough to downgrade one library (fold-to-ascii) to an ES5 version.

Unfortunately, an error message isn't very helpful, so finding the problematic file is unnecessarily difficult. It's hard to tell which file causes the error in Your case, but I can at least say what helped me.

I manually put a log (with help from http://discuss.emberjs.com/t/debugging-failures-in-uglifyjs/7390/6):

```
function js_error(message, filename, line, col, pos) {
    console.log(`message: ${message} / filename: ${filename} / line: ${line}`);
    throw new JS_Parse_Error(message, filename, line, col, pos);
};
```

into js_error function of node_modules/uglify-js/lib/parse.js (line 205 in my case), and got a message that was actually helpful:

```
message: SyntaxError: Unexpected token: name (ASCIIFolder) / file: 0 / line: 64911 / position: 2070881
```

Then, with the find in path search on text "ASCIIFolder", I was able to locate the problematic files.

Also it may be necessary to do 'clean' install of npm and bower packages (https://emberigniter.com/update-latest-ember-data-cli/):

```
npm cache clean && bower cache clean
rm -rf node_modules bower_components dist tmp
npm install
bower install
```

Alternatively You can completely disable minifying of vendor.js with [https://ember-cli.com/asset-compilation#exclude-from-minification] (although it's not the greatest solution):

```
// ember-cli-build.js
var EmberApp = require('ember-cli/lib/broccoli/ember-app');
module.exports = function(defaults) {
  var app = new EmberApp(defaults, {
    minifyJS: {
      options: {
        exclude: ["**/vendor.js"]
      }
    }
  });

//...
  return app.toTree();
};
```

which tells broccoli-uglify-sourcemap to ignore vendor.js and, therefore, should prevent an error from happening.

The Broccoli Plugin: [UglifyWriter] failed with

Solution

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