minor fix

SAS/TMSS/backend/services/scheduling/lib/constraints.py

@@ -483,6 +483,7 @@ def can_run_at(scheduling_unit: models.SchedulingUnitBlueprint, proposed_start_t
     '''determine if the given scheduling_unit can run withing the given timewindow evaluating all constraints from the "constraints" version 1 template
     :param raise_if_interruped: a callable function which raises under an externally set condition (an 'interrupt' flag was set). This function is/can_be used to interrupt a long-running scheduling call to do an early exit and start a new scheduling call. Default used function is noop (no-operation), thus no interruptable behaviour.
     '''
+    try:
         if gridder is None:
             gridder = Gridder()
 
@@ -499,6 +500,9 @@ def can_run_at(scheduling_unit: models.SchedulingUnitBlueprint, proposed_start_t
             return False
 
         return True
+    except Exception as e:
+        logger.error("can_run_at: unit id=%s proposed_start_time='%s' %s", scheduling_unit.id, proposed_start_time, e)
+        return False
 
 
 def can_run_before(scheduling_unit: models.SchedulingUnitBlueprint, proposed_start_time: datetime, gridder: Gridder) -> bool: