[FIX] Add warning back in (#4880)

Fixes #4869 

As far as I can see, @ToniSkulj removed this warning in #4320, I suspect by accident, but if not, let me know :) 

See:
<img width="1116" alt="image" src="https://github.com/hedyorg/hedy/assets/1003685/4c8d2319-6a9f-4772-8f3b-2541417bcff3">

**How to test**
Observe that code with a space at the start runs but also throws an error:

<img width="701" alt="image" src="https://github.com/hedyorg/hedy/assets/1003685/29e2191f-dbc8-4063-91ef-ebf24a1a896e">

static/js/app.ts

@@ -545,6 +545,11 @@ export async function runit(level: number, lang: string, disabled_prompt: string
         program_data = response;
         console.log('Response', response);
 
+        if (response.Warning && $('#editor').is(":visible")) {
+          //storeFixedCode(response, level);
+          error.showWarning(ClientMessages['Transpile_warning'], response.Warning);
+        }
+
         showAchievements(response.achievements, false, "");
         if (adventure && response.save_info) {
           adventure.save_info = response.save_info;