fix: handle potential undefined result in NativeWatchFileSystem and improve error handling in DiskWatcher

Author: GiveMe-A-Name

crates/rspack_fs/src/watcher/disk_watcher.rs

@@ -88,9 +88,16 @@ impl DiskWatcher {
     for pattern in already_watched_paths.difference(&current_should_watch_paths) {
       // If the path is no longer in the patterns to watch, unwatch it
       if let Some(watcher) = &mut self.inner {
-        watcher
-          .unwatch(pattern)
-          .map_err(|e| rspack_error::error!(e))?;
+        // FIXME:
+        // we will unwatch the path is unnecessary, but we don't have a way to check if the path is still in the patterns
+        // notify will remove the watch path when path is removed in it's inner.
+        // If we unwatch the path again, it will return a error.
+        // So we just ignore the error here.
+        if let Err(e) = watcher.unwatch(pattern) {
+          if !matches!(e.kind, notify::ErrorKind::WatchNotFound) {
+            return Err(rspack_error::error!(e));
+          }
+        }
       }
     }
 

packages/rspack/src/NativeWatchFileSystem.ts

@@ -105,14 +105,17 @@ export default class NativeWatchFileSystem implements WatchFileSystem {
 			[Array.from(directories.added!), Array.from(directories.removed!)],
 			[Array.from(missing.added!), Array.from(missing.removed!)],
 			(err: Error | null, result) => {
-				const { changedFiles, removedFiles } = result;
-
-				const fs = this.#inputFileSystem;
-				for (const item of changedFiles) {
-					fs.purge?.(item);
-				}
-				for (const item of removedFiles) {
-					fs.purge?.(item);
+				// !!if there is an error, result maybe a undefined value
+				const changedFiles = result?.changedFiles || [];
+				const removedFiles = result?.removedFiles || [];
+				if (this.#inputFileSystem?.purge) {
+					const fs = this.#inputFileSystem;
+					for (const item of changedFiles) {
+						fs.purge?.(item);
+					}
+					for (const item of removedFiles) {
+						fs.purge?.(item);
+					}
 				}
 
 				// TODO: add fileTimeInfoEntries and contextTimeInfoEntries