fix: invalidate project file cache and handle watcher race condition (#2779)

#2773

This delays the file reading in svelte-check --watch until we're sure the new file is a project file. I still added a file existence check before reading, but it might be more of a fail-safe because the chance of it being deleted at this point is much smaller.

While checking this, I also found that the new file watch is broken because it now caches the tsconfig parsing result. So I changed the "read the config again" logic to the one language server used to invalidate the project files cache.

Author: jasonlyu123

packages/language-server/src/plugins/typescript/service.ts

@@ -716,7 +716,14 @@ async function createLanguageService(
 
     function fileBelongsToProject(filePath: string, isNew: boolean): boolean {
         filePath = normalizePath(filePath);
-        return hasFile(filePath) || (isNew && getParsedConfig().fileNames.includes(filePath));
+        if (hasFile(filePath)) {
+            return true;
+        }
+        if (!isNew) {
+            return false;
+        }
+        ensureProjectFileUpdates(filePath);
+        return snapshotManager.isProjectFile(filePath);
     }
 
     function updateTsOrJsFile(fileName: string, changes?: TextDocumentContentChangeEvent[]): void {

packages/svelte-check/src/index.ts

@@ -191,8 +191,17 @@ class DiagnosticsWatcher {
     }
 
     private async updateDocument(path: string, isNew: boolean) {
-        const text = fs.readFileSync(path, 'utf-8');
-        await this.svelteCheck.upsertDocument({ text, uri: URI.file(path).toString() }, isNew);
+        await this.svelteCheck.upsertDocument(
+            {
+                // delay reading until we actually need the text
+                // prevents race conditions from crashing svelte-check when something is created and deleted immediately afterwards
+                get text() {
+                    return fs.existsSync(path) ? fs.readFileSync(path, 'utf-8') : '';
+                },
+                uri: URI.file(path).toString()
+            },
+            isNew
+        );
         this.scheduleDiagnostics();
     }