Merge branch 'main' of https://github.com/microsoft/promptflow into d…

…evs/peiwen/add_error_handling

src/promptflow/promptflow/executor/_dag_manager.py

@@ -1,6 +1,7 @@
 import inspect
 from typing import Any, Callable, Dict, List, Mapping
 
+from promptflow._utils.logger_utils import logger
 from promptflow.contracts.flow import InputAssignment, InputValueType, Node
 from promptflow.executor import _input_assignment_parser
 
@@ -67,6 +68,10 @@ def get_node_valid_inputs(self, node: Node, f: Callable) -> Mapping[str, Any]:
                     continue
                 # If the parameter has no default value, the input will be set to None so that function will not fail.
                 else:
+                    logger.warning(
+                        f"The node '{i.value}' referenced by the input '{name}' of the current node '{node.name}' "
+                        "has been bypassed, and no default value is set. Will use 'None' as the value for this input."
+                    )
                     results[name] = None
             else:
                 results[name] = self._get_node_dependency_value(i)