AI chat: Fix bots giving { replies when the llm is busy and does not …

…return something with the startpattern.

playerbot/PlayerbotLLMInterface.cpp

@@ -344,7 +344,7 @@ inline std::string extractAfterPattern(const std::string& content, const std::st
         return content.substr(start_pos);
     }
     else {
-        return content;
+        return "";
     }
 
 }