Browser-sync: Startup in "server" mode gives "UnhandledPromiseRejectionWarning" in Node 6.7.0

[Codelica]

Issue details

When starting BrowserSync in "server" mode, the following warning is given:

(node:1362) UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 1): Error: Exited with code 3

Steps to reproduce/test case

browserSync.init() with "server" option configured. Removing server option/configuration gets rid of warning.

Please specify which version of Browsersync, node and npm you're running

• Browsersync [ 2.17.3 ]
• Node [ 6.7.0 ]

• Npm [ 3.10.3 ]

  Affected platforms

• [X] linux

• [? ] windows
• [? ] OS X
• [? ] freebsd
• [? ] solaris

• [ ] other _(please specify which)_

  Browsersync use-case

• [ ] API

• [X] Gulp
• [ ] Grunt
• [ ] CLI
  

  If CLI, please paste the entire command below

{cli command here}

for all other use-cases, (gulp, grunt etc), please show us exactly how you're using Browsersync

  browserSync.init({
      server: "./web",
      port: 8000,
      ui: {
        port: 8001
      }

[silverstripesk]

I can confirm this BUG, same with 6.8.0 and browsersync 2.14 - 2.17.
2.13 works without warning.

[shakyShane]

I cannot reproduce this bug - it's likely some other module (in your gulp build for example) causing this.

Please try with browser-sync only and you should see this resolved

[Codelica]

I'm afraid I don't think this is an external issue, as I can replicate with pure browser-sync when running on a _headless/browserless_ Linux system:

var browserSync = require('browser-sync').create();

browserSync.init({
  server: {
    baseDir: "./web"
  }
});

Which issues warning (but does work):

(node:16004) UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 1): Error: Exited with code 3

Same code on Mac OS has no warning and browser is opened.

[oduska]

Same here. Fresh install of Ubuntu Server 16.04 and only using the CLI option, not Gulp or any other packages.

[fastfedora]

I'm getting the same error running in a Linux Docker container. If I comment out BrowserSync, the error disappears.

[alexturpin]

I am getting the same issue, definitely caused by BrowserSync. @shakyShane can we reopen this issue now that many users have chimed in with minimal examples yielding similar results?

[shakyShane]

Could someone using the API paste the following before Browsersync and paste the results

process.on('unhandledRejection', (reason) => {
    console.log('Reason: ' + reason);
});

[alexturpin]

@shakyShane Unfortunately not much help I'm afraid:

Reason: Error: Exited with code 3

[Codelica]

_Purely a guess_, but my hunch is that it's related to trying to open a local browser window. As I've personally only seen it appear on browser-less Linux systems.

[alexturpin]

@Codelica good call, that seems to be exactly what's going on! I'm using it from a headless Linux VM and setting open to false makes the error disappear!

[alexturpin]

Okay the problem is here https://github.com/BrowserSync/browser-sync/blob/master/lib/utils.js#L183

We should be adding a catch handler to the promise returned by opn. I'm happy to make a pull request @shakyShane if you tell me what you'd like to happen in this scenario?

[shakyShane]

@alexturpin add then/catch and just console.log the error with a prefix explaining where the error came from (calling the opn module)

Normally I would suggest something cleaner but in this case the callers of the function are not setup for a promise chain so it's the best we can do for now.

[alexturpin]

Just pushed #1246. I did as best as I could to preserve current structure but don't hesitate to alter if something could have been done better.

[patelpriyank]

i can confirm it is a bug on Mac OSX Sierra too with all latest packages

[shakyShane]

Fixed https://github.com/BrowserSync/browser-sync/commit/15e0f1e2fba14d5fece1cc68fab32bf092c05711

released to npm v 2.18.2

[yveslange]

Hi, seems that issue is back in 2.26.7

(node:924) UnhandledPromiseRejectionWarning: Error: Exited with code 3
    at ChildProcess.<anonymous> (/mnt/c/Users/kursion.000/AppData/Roaming/npm/node_modules/browser-sync/node_modules/opn/index.js:83:13)
    at Object.onceWrapper (events.js:288:20)
    at ChildProcess.emit (events.js:200:13)
    at maybeClose (internal/child_process.js:1021:16)
    at Socket.<anonymous> (internal/child_process.js:430:11)
    at Socket.emit (events.js:200:13)
    at Pipe.<anonymous> (net.js:588:12)
(node:924) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async fun
ction without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 1)
(node:924) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not hand
led will terminate the Node.js process with a non-zero exit code.