fs: improve fs.watch ENOSPC error message

Providing `No space left on device` is misleading in this case.
Replace it with something that describes it more accurately.

Refs: https://stackoverflow.com/questions/22475849/node-js-error-enospc/32600959

PR-URL: https://github.com/nodejs/node/pull/21846
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>

1 files changed, 4 insertions, 1 deletions

diff --git a/lib/internal/fs/watchers.js b/lib/internal/fs/watchers.js
index 3db3a5cc7c..758fb4e692 100644
--- a/lib/internal/fs/watchers.js
+++ b/lib/internal/fs/watchers.js
@@ -7,6 +7,7 @@ const {
   StatWatcher: _StatWatcher
 } = process.binding('fs');
 const { FSEvent } = internalBinding('fs_event_wrap');
+const { UV_ENOSPC } = internalBinding('uv');
 const { EventEmitter } = require('events');
 const {
   getStatsFromBinding,
@@ -165,7 +166,9 @@ FSWatcher.prototype.start = function(filename,
     const error = errors.uvException({
       errno: err,
       syscall: 'watch',
-      path: filename
+      path: filename,
+      message: err === UV_ENOSPC ?
+        'System limit for number of file watchers reached' : ''
     });
     error.filename = filename;
     throw error;