fixed file open error, it works!

.vscode/extensions.json

@@ -1,8 +1,10 @@
 {
+    // See http://go.microsoft.com/fwlink/?LinkId=827846
+    // for the documentation about the extensions.json format
     "recommendations": [
         "ms-vscode.cpptools",
-        "wayou.vscode-todo-highlight",
+        "platformio.platformio-ide",
         "usernamehw.errorlens",
-        "platformio.platformio-ide"
+        "wayou.vscode-todo-highlight"
     ]
-}
+}