fix: handle none value in tool node

api/core/workflow/nodes/tool/entities.py

@@ -41,6 +41,10 @@ class ToolNodeData(BaseNodeData, ToolEntity):
         def check_type(cls, value, validation_info: ValidationInfo):
             typ = value
             value = validation_info.data.get("value")
+
+            if value is None:
+                return typ
+
             if typ == "mixed" and not isinstance(value, str):
                 raise ValueError("value must be a string")
             elif typ == "variable":
@@ -54,3 +58,22 @@ class ToolNodeData(BaseNodeData, ToolEntity):
             return typ
 
     tool_parameters: dict[str, ToolInput]
+
+    @field_validator("tool_parameters", mode="before")
+    @classmethod
+    def filter_none_tool_inputs(cls, value):
+        if not isinstance(value, dict):
+            return value
+
+        return {
+            key: tool_input
+            for key, tool_input in value.items()
+            if tool_input is not None and cls._has_valid_value(tool_input)
+        }
+
+    @staticmethod
+    def _has_valid_value(tool_input):
+        """Check if the value is valid"""
+        if isinstance(tool_input, dict):
+            return tool_input.get("value") is not None
+        return getattr(tool_input, "value", None) is not None