Handle exception raised when celery is still processing checks

Sentry Issue: WAVEQC-18

ValueError: setting an array element with a sequence. The requested array has an inhomogeneous shape after 1 dimensions. The detected shape was (1274,) + inhomogeneous part.
(11 additional frame(s) were not displayed)
...
  File "waveqc/views.py", line 453, in network_full_detail
    return self.context(query, label, pk, items)
  File "waveqc/views.py", line 310, in context
    results=self.build_z_values(query),
  File "waveqc/views.py", line 199, in build_z_values
    return np.array(