Emacs lock files cause an UnhandledPromiseRejectionWarning in ng serve

[vbraun]

🐞 Bug report

Command (mark with an x)

• new
• build
• serve
• test
• e2e
• generate
• add
• update
• lint
• xi18n
• run
• config
• help
• version
• doc

Description

Emacs lock files cause an UnhandledPromiseRejectionWarning. The lock file .#filename is actually a symlink pointing nowhere and seems to break the webpack watcher. Also, the lock file is generated once I type anything into the emacs buffer (and not while saving), so there is no point in watching the lock files.

$ npm run start
[...]
chunk {main} main.js, main.js.map (main) 57.7 kB [initial] [rendered]
chunk {polyfills} polyfills.js, polyfills.js.map (polyfills) 141 kB [initial] [rendered]
chunk {runtime} runtime.js, runtime.js.map (runtime) 6.15 kB [entry] [rendered]
chunk {styles} styles.js, styles.js.map (styles) 12.9 kB [initial] [rendered]
chunk {vendor} vendor.js, vendor.js.map (vendor) 2.41 MB [initial] [rendered]
Date: 2020-07-23T08:30:17.123Z - Hash: 86e8ae79c0fc07f7c92b - Time: 5696ms
** Angular Live Development Server is listening on localhost:4200, open your browser on http://localhost:4200/ **
: Compiled successfully.
(node:3270950) UnhandledPromiseRejectionWarning: Error: ENOENT: no such file or directory, stat '/home/vbraun/myproject/src/.#main.ts'
(node:3270950) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag `--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 2)

Apart from flooding the console with spurious errors the watch&rebuild seems to work

🔬 Minimal Reproduction

$ npx ng new
$ cd myproject
$ npm run start
$ emacs src/main.ts

🌍 Your Environment

$ npx ng version

     _                      _                 ____ _     ___
    / \   _ __   __ _ _   _| | __ _ _ __     / ___| |   |_ _|
   / △ \ | '_ \ / _` | | | | |/ _` | '__|   | |   | |    | |
  / ___ \| | | | (_| | |_| | | (_| | |      | |___| |___ | |
 /_/   \_\_| |_|\__, |\__,_|_|\__,_|_|       \____|_____|___|
                |___/
    

Angular CLI: 10.0.4
Node: 12.16.3
OS: linux x64

Angular: 2.4.10
... compiler, compiler-cli, core
Ivy Workspace: 

Package                      Version
------------------------------------------------------
@angular-devkit/architect    0.1000.4
@angular-devkit/core         10.0.4
@angular-devkit/schematics   10.0.4
@angular/cli                 10.0.4
@angular/tsc-wrapped         0.5.2
@ngtools/json-schema         1.1.0
@ngtools/webpack             1.10.2
@schematics/angular          10.0.4
@schematics/update           0.1000.4
rxjs                         6.5.5
typescript                   2.0.10
webpack                      2.2.0

[vbraun]

An even easier repro is to just create a dangling symlink in the project root:

$ ln -sf foo bar
$ npx ng serve
[...]
(node:3427060) UnhandledPromiseRejectionWarning: Error: ENOENT: no such file or directory, stat '/home/vbraun/myproject/bar'

[alan-agius4]

@vbraun, I tried to replicate this but I didn't get the mentioned error

➜  test git:(master) ✗ ln -sf foo bar
➜  test git:(master) ✗ ng serve

chunk {main} main.js, main.js.map (main) 60.6 kB [initial] [rendered]
chunk {polyfills} polyfills.js, polyfills.js.map (polyfills) 141 kB [initial] [rendered]
chunk {runtime} runtime.js, runtime.js.map (runtime) 6.15 kB [entry] [rendered]
chunk {styles} styles.js, styles.js.map (styles) 13.5 kB [initial] [rendered]
chunk {vendor} vendor.js, vendor.js.map (vendor) 2.64 MB [initial] [rendered]
Date: 2020-07-23T14:18:30.115Z - Hash: 595948837955d0f39f47 - Time: 4809ms
** Angular Live Development Server is listening on localhost:4200, open your browser on http://localhost:4200/ **
: Compiled successfully.

[vbraun]

Hmm, package version mismatch? I've just installed the newest from npm.

Downgrading to chokidar@2.1.8 kludges around the issue for me (either by downgrading to watchpack 1.6.1 or getting rid of watchpack's vendored version):

$ npm install chokidar@2.1.8
$ rm -rf node_modules/watchpack/node_modules/chokidar
$ npx run serve
... no more UnhandledPromiseRejectionWarning ...

I also tried node v10 and v14, but no dice: Still get the same UnhandledPromiseRejectionWarning

[alan-agius4]

@vbraun, so I did try to replicate this again this time in a Linux container and I did manage to replicate it.

This will need some digging.

[vbraun]

This is probably paulmillr/chokidar#955

[glihm]

Exactly the same here, a temporal solution waiting the release might be to add this line in .emacs file:

(setq create-lockfiles nil)

But this solution should only be temporary and/or rely on more often backup files.

[alan-agius4]

Thanks for reporting this issue. This issue is now obsolete due to changes in the recent releases. Please update to the most recent Angular CLI version.

If the problem persists after upgrading, please open a new issue, provide a simple repository reproducing the problem, and describe the difference between the expected and current behavior.

[angular-automatic-lock-bot]

This issue has been automatically locked due to inactivity.
Please file a new issue if you are encountering a similar or related problem.

Read more about our automatic conversation locking policy.

_{This action has been performed automatically by a bot.}