handle model not found error better

backend/main.py

@@ -206,6 +206,18 @@ async def stream_code(websocket: WebSocket):
                 )
             )
             return await throw_error(error_message)
+        except openai.NotFoundError as e:
+            print("[GENERATE_CODE] Model not found", e)
+            error_message = (
+                e.message
+                + ". Please make sure you have followed the instructions correctly to obtain an OpenAI key with GPT vision access: https://github.com/abi/screenshot-to-code/blob/main/Troubleshooting.md"
+                + (
+                    " Alternatively, you can purchase code generation credits directly on this website."
+                    if IS_PROD
+                    else ""
+                )
+            )
+            return await throw_error(error_message)
 
     # Write the messages dict into a log so that we can debug later
     write_logs(prompt_messages, completion)