DX xlsx and csv export fails if patient does not have an age

David Platten reporter

Here's the error that is reported by celery:

[2015-09-02 08:54:06,124: ERROR/MainProcess] Task remapp.exports.dx_export.dxxlsx[4e52dc93-2f75-4500-8073-6b6bb798b9c9] raised unexpected: DoesNotExist('PatientStudyModuleAttr matching query does not exist.',)
Traceback (most recent call last):
  File "C:\Python27\Lib\site-packages\celery\app\trace.py", line 240, in trace_task
    R = retval = fun(*args, **kwargs)
  File "C:\Python27\Lib\site-packages\celery\app\trace.py", line 437, in __protected_call__
    return self.run(*args, **kwargs)
  File "C:\Python27\Lib\site-packages\openrem\remapp\exports\dx_export.py", line 393, in dxxlsx
    str(exams.patientstudymoduleattr_set.get().patient_age_decimal),
  File "C:\Python27\Lib\site-packages\django\db\models\manager.py", line 127, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File "C:\Python27\Lib\site-packages\django\db\models\query.py", line 334, in get
    self.model._meta.object_name
Exception: PatientStudyModuleAttr matching query does not exist.