L2SS-572: improve assert statements

tangostationcontrol/tangostationcontrol/beam/delays.py

@@ -15,7 +15,7 @@ class Delays:
         frame_location = measure.position("ITRF", *[f"{x}m" for x in itrf])
 
         result = measure.do_frame(frame_location)
-        assert result == True
+        assert result == True , f"measure.do_frame failed for ITRF location {itrf}"
 
         self.reference_itrf = itrf
         self.measure = measure
@@ -23,10 +23,11 @@ class Delays:
 
     def set_measure_time(self, utc_time: datetime.datetime):
         """ Configure the measure object for the specified time. """
-        frame_time = self.measure.epoch("UTC", utc_time.isoformat(' '))
+        utc_time_str = utc_time.isoformat(' ')
+        frame_time = self.measure.epoch("UTC", utc_time_str)
 
         result = self.measure.do_frame(frame_time)
-        assert result == True
+        assert result == True , f"measure.do_frame failed for UTC time {utc_time_str}"
 
     def get_direction_vector(self, pointing: numpy.ndarray) -> numpy.ndarray:
         """ Compute direction vector for a given pointing, relative to the measure. """