fix(core/tools): Fix the issue with iterating over None in `_transfor…

…m_tool_parameters_type`. (langgenius#5190)

api/core/tools/tool/tool.py

@@ -237,10 +237,10 @@ def _transform_tool_parameters_type(self, tool_parameters: dict[str, Any]) -> di
         """
         # Temp fix for the issue that the tool parameters will be converted to empty while validating the credentials
         result = deepcopy(tool_parameters)
-        for parameter in self.parameters:
+        for parameter in self.parameters or []:
             if parameter.name in tool_parameters:
                 result[parameter.name] = ToolParameterConverter.cast_parameter_by_type(tool_parameters[parameter.name], parameter.type)
-        
+
         return result
 
     @abstractmethod