fix: handle non-string model_type to prevent AttributeError

When numeric model names (e.g., '1') are used with vLLM and configured
in YAML without quotes, they are parsed as integers. This causes
AttributeError when calling startswith() method.

Changes:
- Add type checking for model_type
- Convert non-string model_type to string with warning log
- Prevents crash when using custom numeric model names

Fixes #2664

bridge/bridge.py

@@ -24,6 +24,13 @@ class Bridge(object):
             self.btype["chat"] = bot_type
         else:
             model_type = conf().get("model") or const.GPT_41_MINI
+            
+            # Ensure model_type is string to prevent AttributeError when using startswith()
+            # This handles cases where numeric model names (e.g., "1") are parsed as integers from YAML
+            if not isinstance(model_type, str):
+                logger.warning(f"[Bridge] model_type is not a string: {model_type} (type: {type(model_type).__name__}), converting to string")
+                model_type = str(model_type)
+            
             if model_type in ["text-davinci-003"]:
                 self.btype["chat"] = const.OPEN_AI
             if conf().get("use_azure_chatgpt", False):