Improper handling of broken symlinks, causes UnhandledPromiseRejectionWarning

[jaens]

When watching a directory with followSymlinks off, if the directory contains links for which the target does not exist, chokidar blows up with:

UnhandledPromiseRejectionWarning: Error: ENOENT: no such file or directory, stat <path of symlink>

This is due to calling fsrealpath on the link, which fails (since the link target does not exist) here:

chokidar/lib/nodefs-handler.js

Line 416 in 7c79e45

const linkPath = await fsrealpath(path);

Note the node.js documentation for fs.realpath:

Asynchronously computes the canonical pathname by resolving ., .. and symbolic links.

(it does not specify what happens when the link target does not exist, but as reality shows it throws ENOENT...)

Perhaps using the fs.readlink function would be more appropriate there.

[jaens]

Looks like fsrealpath is also being used in a similar manner here:

chokidar/lib/nodefs-handler.js

Line 607 in 7c79e45

const targetPath = follow ? await fsrealpath(path) : path;

[rory-ye-nv]

same problem here

[paulmillr]

pull requests are welcome

[nicks]

fwiw, this breaks create-react-app's webpack server hard, because it treats these warnings as errors and crashes the server

The error looks like this:

/home/nick/src/tilt/web/node_modules/react-scripts/scripts/start.js:19
  throw err;
  ^

[Error: ENOENT: no such file or directory, stat '/home/nick/src/tilt/web/src/.#Statusbar.tsx'] {
  errno: -2,
  code: 'ENOENT',
  syscall: 'stat',
  path: '/home/nick/src/tilt/web/src/.#Statusbar.tsx'
}
error Command failed with exit code 1.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.

Here's the stack trace to the call that throws the error.

    at internal/util.js:297:30
    at new Promise (<anonymous>)
    at internal/util.js:296:12
    at NodeFsHandler._handleSymlink (/home/nick/src/tilt/web/node_modules/watchpack/node_modules/chokidar/lib/nodefs-handler.js:433:30)
    at ReaddirpStream.<anonymous> (/home/nick/src/tilt/web/node_modules/watchpack/node_modules/chokidar/lib/nodefs-handler.js:486:23)
    at ReaddirpStream.emit (events.js:321:20)
    at addChunk (_stream_readable.js:294:12)
    at readableAddChunk (_stream_readable.js:275:11)
    at ReaddirpStream.Readable.push (_stream_readable.js:209:10)

I'm happy to send a PR, but is there some reason this isn't as simple as wrapping the unhandled await call in a try...catch block? I'm probably missing something.

[paulmillr]

try adding try catch, adding the failing test, and seeing if that breaks any other tests