Address review comments.

Author: davidmorgan

pkgs/watcher/lib/src/directory_watcher/windows.dart

@@ -199,7 +199,10 @@ class _WindowsDirectoryWatcher
           subscription.onError((Object e, StackTrace stackTrace) {
             _listSubscriptions.remove(subscription);
             // "Path not found" can be caused by creating then quickly removing
-            // a directory: continue without reporting an error.
+            // a directory: continue without reporting an error. Nested files
+            // that get removed during the `list` are already ignored by `list`
+            // itself, so there are no other types of "path not found" that
+            // might need different handling here.
             if (e is! PathNotFoundException) {
               _emitError(e, stackTrace);
             }