fs: ignore deleted dirs in recursive watch scan

[trivikr]

Fixes a race in the non-native recursive fs.watch() implementation.

When a directory is removed recursively, the watcher can observe the child
directory from the parent watcher and then attempt to scan it after it has
already been deleted. In that case, readdirSync() throws ENOENT, which was
emitted as a watcher error and could crash tests with an unhandled error
event.

This treats ENOENT during the recursive directory scan as a normal deletion
race, while preserving existing error reporting for other failures.

Refs: https://github.com/nodejs/reliability/blob/main/reports/2026-06-01.md#jstest-failure

Example Error log

not ok 1330 parallel/test-fs-watch-recursive-delete
  ---
  duration_ms: 826.25800
  severity: fail
  exitcode: 1
  stack: |-
    node:events:487
          throw er; // Unhandled 'error' event
          ^
    
    Error: ENOENT: no such file or directory, scandir '/home/iojs/node-tmp/.tmp.1329/parent/child'
        at readdirSync (node:fs:1554:26)
        at #watchFolder (node:internal/fs/recursive_watch:122:21)
        at FSWatcher.<anonymous> (node:internal/fs/recursive_watch:208:26)
        at FSWatcher.emit (node:events:509:20)
        at FSWatcher._handle.onchange (node:internal/fs/watchers:279:12)
    Emitted 'error' event on FSWatcher instance at:
        at #watchFolder (node:internal/fs/recursive_watch:160:12)
        at FSWatcher.<anonymous> (node:internal/fs/recursive_watch:208:26)
        at FSWatcher.emit (node:events:509:20)
        at FSWatcher._handle.onchange (node:internal/fs/watchers:279:12) {
      errno: -2,
      code: 'ENOENT',
      syscall: 'scandir',
      path: '/home/iojs/node-tmp/.tmp.1329/parent/child'
    }
    
    Node.js v27.0.0-pre
  ...

---

Assisted-by: openai:gpt-5.5

[codecov]

Codecov Report

❌ Patch coverage is 0% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 90.35%. Comparing base (9e58d9d) to head (a80cd49).
⚠️ Report is 4 commits behind head on main.

Files with missing lines	Patch %	Lines
lib/internal/fs/recursive_watch.js	0.00%	3 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #63686   +/-   ##
=======================================
  Coverage   90.34%   90.35%           
=======================================
  Files         732      732           
  Lines      236507   236529   +22     
  Branches    44531    44534    +3     
=======================================
+ Hits       213684   213704   +20     
- Misses      14525    14540   +15     
+ Partials     8298     8285   -13     

Files with missing lines	Coverage Δ
lib/internal/fs/recursive_watch.js	85.37% <0.00%> (+0.10%)	⬆️

... and 33 files with indirect coverage changes

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[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/73847/