TypeError: Cannot read property 'source' of undefined

[AlexDel]

[ webpack 4.1.0, worker-loader 1.1.1]

myService.js
import Worker from './summary.worker';

webpack.config.js
{ test: /\.worker\.js$/, use: { loader: 'worker-loader' } }

On trying to build console emits this:

C:\Users\verba\gg\incubator-ignite\modules\web-console\frontend\node_modules\worker-loader\dist\index.js:121
      worker.factory = (0, _workers2.default)(worker.file, compilation.assets[worker.file].source(), options);
                                                                                              ^
TypeError: Cannot read property 'source' of undefined
    at C:\Users\verba\gg\incubator-ignite\modules\web-console\frontend\node_modules\worker-loader\dist\index.js:121:92
    at compile (C:\Users\verba\gg\incubator-ignite\modules\web-console\frontend\node_modules\webpack\lib\Compiler.js:222:11)
    at hooks.afterCompile.callAsync.err (C:\Users\verba\gg\incubator-ignite\modules\web-console\frontend\node_modules\webpack\lib\Compiler.js:470:14)
    at AsyncSeriesHook.eval [as callAsync] (eval at create (C:\Users\verba\gg\incubator-ignite\modules\web-console\frontend\node_modules\webpack\node_modules\tapable\lib\HookCodeFactory.js:24:12), <anonymous>:6:1)
    at AsyncSeriesHook.lazyCompileHook [as _callAsync] (C:\Users\verba\gg\incubator-ignite\modules\web-console\frontend\node_modules\webpack\node_modules\tapable\lib\Hook.js:35:21)
    at compilation.seal.err (C:\Users\verba\gg\incubator-ignite\modules\web-console\frontend\node_modules\webpack\lib\Compiler.js:467:30)
    at AsyncSeriesHook.eval [as callAsync] (eval at create (C:\Users\verba\gg\incubator-ignite\modules\web-console\frontend\node_modules\webpack\node_modules\tapable\lib\HookCodeFactory.js:24:12), <anonymous>:6:1)
    at AsyncSeriesHook.lazyCompileHook [as _callAsync] (C:\Users\verba\gg\incubator-ignite\modules\web-console\frontend\node_modules\webpack\node_modules\tapable\lib\Hook.js:35:21)
    at hooks.optimizeAssets.callAsync.err (C:\Users\verba\gg\incubator-ignite\modules\web-console\frontend\node_modules\webpack\lib\Compilation.js:957:35)
    at AsyncSeriesHook.eval [as callAsync] (eval at create (C:\Users\verba\gg\incubator-ignite\modules\web-console\frontend\node_modules\webpack\node_modules\tapable\lib\HookCodeFactory.js:24:12), <anonymous>:6:1)
    at AsyncSeriesHook.lazyCompileHook [as _callAsync] (C:\Users\verba\gg\incubator-ignite\modules\web-console\frontend\node_modules\webpack\node_modules\tapable\lib\Hook.js:35:21)
    at hooks.optimizeChunkAssets.callAsync.err (C:\Users\verba\gg\incubator-ignite\modules\web-console\frontend\node_modules\webpack\lib\Compilation.js:948:32)
    at _err0 (eval at create (C:\Users\verba\gg\incubator-ignite\modules\web-console\frontend\node_modules\webpack\node_modules\tapable\lib\HookCodeFactory.js:24:12), <anonymous>:11:1)
    at C:\Users\verba\gg\incubator-ignite\modules\web-console\frontend\node_modules\webpack\node_modules\uglifyjs-webpack-plugin\dist\index.js:262:11
    at _class.runTasks (C:\Users\verba\gg\incubator-ignite\modules\web-console\frontend\node_modules\webpack\node_modules\uglifyjs-webpack-plugin\dist\uglify\index.js:63:9)
    at UglifyJsPlugin.optimizeFn (C:\Users\verba\gg\incubator-ignite\modules\web-console\frontend\node_modules\webpack\node_modules\uglifyjs-webpack-plugin\dist\index.js:182:16)
    at AsyncSeriesHook.eval [as callAsync] (eval at create (C:\Users\verba\gg\incubator-ignite\modules\web-console\frontend\node_modules\webpack\node_modules\tapable\lib\HookCodeFactory.js:24:12), <anonymous>:7:1)
    at AsyncSeriesHook.lazyCompileHook [as _callAsync] (C:\Users\verba\gg\incubator-ignite\modules\web-console\frontend\node_modules\webpack\node_modules\tapable\lib\Hook.js:35:21)
    at hooks.additionalAssets.callAsync.err (C:\Users\verba\gg\incubator-ignite\modules\web-console\frontend\node_modules\webpack\lib\Compilation.js:943:36)
    at AsyncSeriesHook.eval [as callAsync] (eval at create (C:\Users\verba\gg\incubator-ignite\modules\web-console\frontend\node_modules\webpack\node_modules\tapable\lib\HookCodeFactory.js:24:12), <anonymous>:6:1)
    at AsyncSeriesHook.lazyCompileHook [as _callAsync] (C:\Users\verba\gg\incubator-ignite\modules\web-console\frontend\node_modules\webpack\node_modules\tapable\lib\Hook.js:35:21)
    at hooks.optimizeTree.callAsync.err (C:\Users\verba\gg\incubator-ignite\modules\web-console\frontend\node_modules\webpack\lib\Compilation.js:939:32)
    at AsyncSeriesHook.eval [as callAsync] (eval at create (C:\Users\verba\gg\incubator-ignite\modules\web-console\frontend\node_modules\webpack\node_modules\tapable\lib\HookCodeFactory.js:24:12), <anonymous>:6:1)
    at AsyncSeriesHook.lazyCompileHook [as _callAsync] (C:\Users\verba\gg\incubator-ignite\modules\web-console\frontend\node_modules\webpack\node_modules\tapable\lib\Hook.js:35:21)
    at Compilation.seal (C:\Users\verba\gg\incubator-ignite\modules\web-console\frontend\node_modules\webpack\lib\Compilation.js:881:27)
    at hooks.make.callAsync.err (C:\Users\verba\gg\incubator-ignite\modules\web-console\frontend\node_modules\webpack\lib\Compiler.js:464:17)
    at _err0 (eval at create (C:\Users\verba\gg\incubator-ignite\modules\web-console\frontend\node_modules\webpack\node_modules\tapable\lib\HookCodeFactory.js:24:12), <anonymous>:11:1)
    at _addModuleChain (C:\Users\verba\gg\incubator-ignite\modules\web-console\frontend\node_modules\webpack\lib\Compilation.js:749:12)
    at processModuleDependencies.err (C:\Users\verba\gg\incubator-ignite\modules\web-console\frontend\node_modules\webpack\lib\Compilation.js:688:9)
    at _combinedTickCallback (internal/process/next_tick.js:131:7)
    at process._tickCallback (internal/process/next_tick.js:180:9)

[akuznetsov-gridgain]

+1 I also need this fix.

[AlexDel]

The porblem appeared to be in broken eslint-loader, which piped undefined object to worker-loader. Hope that will help somebody.

[huy-nguyen]

@AlexDel I got the same error with the same call stack but didn't use eslint-loader. I'm on webpack 4.2.0 and worker-loader 1.1.1. If anyone knows where to start debugging, I can give it a try.

[Manc]

If anybody comes across this in the future – this is what caused the problem for me and a solution.

I set the name option to w.[contenthash:8].js, which caused the error from above, but only when I ran Webpack in development mode (production mode was fine).

My solution:

use: [
	{
		loader: 'worker-loader',
		name: isDev ? 'w.[hash].js' : 'w.[contenthash:8].js',
	},
]

Or simply use [hash] in both cases, of course.

[eranimo]

Also getting this error, rather randomly. Also on Webpack 4, no eslint-loader.

[futurechallenger]

When I try to use the inline mode, I met this problem too. Here's how I solved this problem:

  {
    // loader: 'worker-loader',
    // options: {
    //   inline: true, 
    //   fallback: false,
    // }
    test: /\.worker\.js$/,
    use: { 
      loader: 'worker-loader',
      options: {
          inline: true, 
          fallback: false,
        }
    },
  },