fix(qa_service): fix log placement and add KeyError→LLMParseError handling

app/services/qa_service.py

@@ -3,6 +3,7 @@ import base64
 from app.clients.llm.base import LLMClient
 from app.clients.storage.base import StorageClient
 from app.core.config import get_config
+from app.core.exceptions import LLMParseError
 from app.core.json_utils import extract_json
 from app.core.logging import get_logger
 from app.models.qa_models import (
@@ -47,10 +48,15 @@ async def gen_text_qa(req: GenTextQARequest, llm: LLMClient) -> TextQAResponse:
     messages = [{"role": "user", "content": prompt}]
     raw = await llm.chat(model, messages)
 
+    items_raw = extract_json(raw)
     logger.info("gen_text_qa", extra={"items": len(req.items), "model": model})
 
-    items_raw = extract_json(raw)
+    if not isinstance(items_raw, list):
+        raise LLMParseError("大模型返回的问答对格式不正确")
+    try:
         pairs = [QAPair(question=item["question"], answer=item["answer"]) for item in items_raw]
+    except (KeyError, TypeError):
+        raise LLMParseError("大模型返回的问答对格式不正确")
     return TextQAResponse(pairs=pairs)
 
 
@@ -91,9 +97,13 @@ async def gen_image_qa(
         ]
 
         raw = await llm.chat_vision(model, messages)
-        logger.info("gen_image_qa", extra={"path": item.cropped_image_path, "model": model})
 
         items_raw = extract_json(raw)
+        logger.info("gen_image_qa", extra={"path": item.cropped_image_path, "model": model})
+
+        if not isinstance(items_raw, list):
+            raise LLMParseError("大模型返回的问答对格式不正确")
+        try:
             for qa in items_raw:
                 pairs.append(
                     ImageQAPair(
@@ -102,5 +112,7 @@ async def gen_image_qa(
                         image_path=item.cropped_image_path,
                     )
                 )
+        except (KeyError, TypeError):
+            raise LLMParseError("大模型返回的问答对格式不正确")
 
     return ImageQAResponse(pairs=pairs)