fix: add logging for missing edge mapping in StreamProcessor (#12008)

Signed-off-by: -LAN- <laipz8200@outlook.com>

api/core/workflow/nodes/answer/base_stream_processor.py

+import logging
 from abc import ABC, abstractmethod
 from collections.abc import Generator
 
 from core.workflow.graph_engine.entities.event import GraphEngineEvent, NodeRunSucceededEvent
 from core.workflow.graph_engine.entities.graph import Graph
 
+logger = logging.getLogger(__name__)
+
 
 class StreamProcessor(ABC):
     def __init__(self, graph: Graph, variable_pool: VariablePool) -> None:
         if run_result.edge_source_handle:
             reachable_node_ids = []
             unreachable_first_node_ids = []
+            if finished_node_id not in self.graph.edge_mapping:
+                logger.warning(f"node {finished_node_id} has no edge mapping")
+                return
             for edge in self.graph.edge_mapping[finished_node_id]:
                 if (
                     edge.run_condition