Job status: do not attempt to check if checker failed if last_checked_at is None

app/models/delayed_job_models.py

@@ -215,6 +215,9 @@ class DelayedJob(DB.Model):
         """
         :return: True if the checker seems to have died, false otherwise
         """
+        if self.last_lsf_checked_at is None:
+            return False
+
         lsf_script_errored = self.last_lsf_check_status != 0
         death_assumption_seconds = RUN_CONFIG.get('status_agent').get('death_assumption_seconds')
         checker_assumed_dead_time = app_utils.get_utc_now() - datetime.timedelta(seconds=death_assumption_seconds)