fix: loop exit condition accepts variables from nodes inside the loop #24183: (#24257)

Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>

api/core/workflow/nodes/loop/loop_node.py

                 and event.node_type == NodeType.LOOP_END
                 and not isinstance(event, NodeRunStreamChunkEvent)
             ):
-                check_break_result = True
-                yield self._handle_event_metadata(event=event, iter_run_index=current_index)
-                break
-
-            if isinstance(event, NodeRunSucceededEvent):
-                yield self._handle_event_metadata(event=event, iter_run_index=current_index)
-
-                # Check if all variables in break conditions exist
-                exists_variable = False
+                # Check if variables in break conditions exist and process conditions
+                # Allow loop internal variables to be used in break conditions
+                available_conditions = []
                 for condition in break_conditions:
-                    if not self.graph_runtime_state.variable_pool.get(condition.variable_selector):
-                        exists_variable = False
-                        break
-                    else:
-                        exists_variable = True
-                if exists_variable:
+                    variable = self.graph_runtime_state.variable_pool.get(condition.variable_selector)
+                    if variable:
+                        available_conditions.append(condition)
+
+                # Process conditions if at least one variable is available
+                if available_conditions:
                     input_conditions, group_result, check_break_result = condition_processor.process_conditions(
                         variable_pool=self.graph_runtime_state.variable_pool,
-                        conditions=break_conditions,
+                        conditions=available_conditions,
                         operator=logical_operator,
                     )
                     if check_break_result:
                         break
+                else:
+                    check_break_result = True
+                yield self._handle_event_metadata(event=event, iter_run_index=current_index)
+                break
+
+            if isinstance(event, NodeRunSucceededEvent):
+                yield self._handle_event_metadata(event=event, iter_run_index=current_index)
 
             elif isinstance(event, BaseGraphEvent):
                 if isinstance(event, GraphRunFailedEvent):