Update src/containers/extension-library.jsx

src/containers/extension-library.jsx

@@ -28,6 +28,12 @@ const messages = defineMessages({
         defaultMessage: 'This extension is incompatible with Scratch. Projects made with it cannot be uploaded to the Scratch website. Are you sure you want to enable it?',
         description: 'Confirm loading Scratch-incompatible extension',
         id: 'tw.confirmIncompatibleExtension'
+    },
+    extensionWarning: {
+        // eslint-disable-next-line max-len
+        defaultMessage: 'This extension is not recommended for real projects. It may be unstable and cause problems with your project later on. Are you sure you want to enable it?',
+        description: 'Confirm loading buggy and unstable extension',
+        id: 'pm.confirmBuggyUnstableExtension'
     }
 });