feat: implement error handling and status messaging for streaming chat completions

app.py

@@ -24,6 +24,8 @@ def chat(messages: list, system_prompt: str = "") -> str:
     for msg in messages:
         formatted.append({"role": msg["role"], "content": msg["content"]})
     completion = client.chat.completions.create(model=MODEL, messages=formatted)
+    if not completion.choices:
+        return "Error: No response from model."
     return completion.choices[0].message.content
 
 
@@ -39,13 +41,18 @@ async def stream_chat(request: Request):
         formatted.append({"role": msg["role"], "content": msg["content"]})
 
     def event_stream():
-        stream = client.chat.completions.create(
-            model=MODEL, messages=formatted, stream=True
-        )
-        for chunk in stream:
-            delta = chunk.choices[0].delta
-            if delta.content:
-                yield f"data: {json.dumps({'token': delta.content})}\n\n"
+        try:
+            stream = client.chat.completions.create(
+                model=MODEL, messages=formatted, stream=True
+            )
+            for chunk in stream:
+                if not chunk.choices:
+                    continue
+                delta = chunk.choices[0].delta
+                if delta.content:
+                    yield f"data: {json.dumps({'token': delta.content})}\n\n"
+        except Exception as e:
+            yield f"data: {json.dumps({'error': str(e)})}\n\n"
         yield "data: [DONE]\n\n"
 
     return StreamingResponse(event_stream(), media_type="text/event-stream")

index.html

@@ -684,13 +684,20 @@
                     
                     for (const line of lines) {
                         if (line.startsWith('data: ')) {
-                            const data = line.slice(6);
+                            const data = line.slice(6).trim();
                             if (data === '[DONE]') break;
                             try {
                                 const parsed = JSON.parse(data);
-                                accumulated += parsed.token;
-                                aiMsgEl.innerHTML = marked.parse(accumulated);
-                                chatContainer.scrollTop = chatContainer.scrollHeight;
+                                if (parsed.error) {
+                                    accumulated = `<span style="color: #ef4444;">Error: ${parsed.error}</span>`;
+                                    aiMsgEl.innerHTML = accumulated;
+                                    break;
+                                }
+                                if (parsed.token) {
+                                    accumulated += parsed.token;
+                                    aiMsgEl.innerHTML = marked.parse(accumulated);
+                                    chatContainer.scrollTop = chatContainer.scrollHeight;
+                                }
                             } catch (e) {}
                         }
                     }