uncaughtPromiseRejection causing webpack to hang

[gdborton]

Library Affected: workbox-webpack-plugin

Browser & Platform: OSX, node v6.10.2, npm v2.15.12

Issue or Feature Request Description:

Including this plugin in our webpack config w/ webpack's node api prevents surfacing build errors and results in hung builds when errors are present. Using a config like so...

const webpack = require('webpack');
const config = require('./myWebpackConfigWithWorkbox');

const compiler = webpack(config);
compiler.run(() => {
  throw new Error('this should cause the program to exit 1');
});

^ this config results in our compile script never exiting and a message about an unhandled rejection. Removing workbox-webpack-plugin makes the script behave as expected. As a short term work around for this we've included the below snippet.

process.on('unhandledRejection', (reason) => {
  console.log('Found an unhandled promise rejection. Rethrowing to surface the error.');
  throw reason;
});

Let me know if this isn't enough information to reproduce and I'll throw up a repo that demonstrates the problem.

[prateekbh]

@gdborton, any stack trace and your webpack version would be really helpful

[gdborton]

@prateekbh I'm afraid that the stack trace wouldn't be very helpful.

/Users/gary_borton/airlab/repos/airbnb/webpack/compile.js:50
  throw reason;
  ^

Error: asdf
    at multiCompiler.run (/Users/gary_borton/airlab/repos/airbnb/webpack/compile.js:22:9)
    at runWithDependencies (/Users/gary_borton/airlab/repos/airbnb/node_modules/webpack/lib/MultiCompiler.js:153:19)
    at /Users/gary_borton/airlab/repos/airbnb/node_modules/webpack/node_modules/async/dist/async.js:1074:9
    at /Users/gary_borton/airlab/repos/airbnb/node_modules/webpack/node_modules/async/dist/async.js:421:16
    at iteratorCallback (/Users/gary_borton/airlab/repos/airbnb/node_modules/webpack/node_modules/async/dist/async.js:996:13)
    at /Users/gary_borton/airlab/repos/airbnb/node_modules/webpack/node_modules/async/dist/async.js:906:16
    at /Users/gary_borton/airlab/repos/airbnb/node_modules/webpack/node_modules/async/dist/async.js:1071:13
    at fn (/Users/gary_borton/airlab/repos/airbnb/node_modules/webpack/lib/MultiCompiler.js:99:21)
    at compiler.run (/Users/gary_borton/airlab/repos/airbnb/node_modules/webpack/lib/MultiCompiler.js:148:20)
    at /Users/gary_borton/airlab/repos/airbnb/node_modules/webpack/lib/Compiler.js:250:22

I've gotten this issue with workbox-webpack-plugin @1.0.0 and @1.1.0 and with webpack @2.3.2 and 3.1.0

While trying to create a repo to reproduce the problem, I noticed that it only seems to happen in conjunction with our use of happypack. Removing either happypack or this plugin makes the issue go away.

[gdborton]

Ooph seems even more complicated than that, we've also got SWPrecache and disabling any of these three plugins makes the build exit with an error code as expected... If I had to guess I'd say this is an issue with happypack, but haven't yet been able to reproduce in a small repo.

[jeffposnick]

Closing for now. Please reopen if you have clear reproduction steps or a better idea or what's going on.