refactor: Make sure start_from_trigger is not None to be able to start task directly in deferred mode

Author: dabla

airflow-core/src/airflow/models/taskinstance.py

@@ -1454,8 +1454,7 @@ def defer_task(self, session: Session = NEW_SESSION) -> bool:
 
         context = self.get_template_context()
 
-        if self.task and self.task.expand_start_from_trigger(context=context):
-            start_trigger_args = self.task.expand_start_trigger_args(context=context)
+        if self.task and self.task.expand_start_from_trigger(context=context) and (start_trigger_args := self.task.expand_start_trigger_args(context=context)):
             trigger_kwargs = start_trigger_args.trigger_kwargs or {}
             timeout = self.task.start_trigger_args.timeout
 
@@ -1465,7 +1464,6 @@ def defer_task(self, session: Session = NEW_SESSION) -> bool:
             else:
                 self.trigger_timeout = None
 
-            print(">>> Creating trigger from context start_trigger_args: {}".format(trigger_kwargs))
             trigger_row = Trigger(
                 classpath=start_trigger_args.trigger_cls,
                 kwargs=trigger_kwargs,