fix: handle none value in agent node tool settings

api/core/workflow/nodes/agent/agent_node.py

@@ -164,7 +164,8 @@ class AgentNode(ToolNode):
                         params = {}
                         for key, param in parameters.items():
                             if param.get("auto", ParamsAutoGenerated.OPEN.value) == ParamsAutoGenerated.CLOSE.value:
-                                params[key] = param.get("value", {}).get("value", "")
+                                value_param = param.get("value", {})
+                                params[key] = value_param.get("value", "") if value_param is not None else None
                             else:
                                 params[key] = None
                         parameters = params