refac: reasoning detection

backend/open_webui/utils/middleware.py

@@ -1422,8 +1422,10 @@ async def process_chat_response(
                             if after_tag:
                                 content_blocks[-1]["content"] = after_tag
 
+                            content = after_tag
                             break
-                elif content_blocks[-1]["type"] == content_type:
+
+                if content and content_blocks[-1]["type"] == content_type:
                     start_tag = content_blocks[-1]["start_tag"]
                     end_tag = content_blocks[-1]["end_tag"]
                     # Match end tag e.g., </tag>