Fix handling notebook cell closed

src/extension.ts

@@ -214,9 +214,22 @@ export function activate(context: ExtensionContext) {
 
     async function didCloseTextDocument(document: TextDocument) {
         if (document.uri.scheme === 'untitled') {
-            return;
+            const result = workspace.textDocuments.find((doc) => doc.uri.scheme === 'untitled');
+            if (result) {
+                // Stop the langauge server when all untitled documents are closed.
+                return;
+            }
+        }
+
+        if (document.uri.scheme === 'vscode-notebook-cell') {
+            const result = workspace.textDocuments.find((doc) => doc.uri.fsPath === document.uri.fsPath);
+            if (result) {
+                // Stop the language server when all cell documents are closed (notebook closed).
+                return;
+            }
         }
 
+        // Stop the language server when single file outside workspace is closed, or the above cases.
         const key = getKey(document.uri);
         let client = clients.get(key);
         if (client) {