KeyError: 'children'

[sentry]

Sentry Issue: ONADATA-2E7

KeyError: 'children'
(11 additional frame(s) were not displayed)
...
  File "onadata/libs/serializers/merged_xform_serializer.py", line 129, in has_matching_fields
    get_merged_xform_survey(value)
  File "onadata/libs/serializers/merged_xform_serializer.py", line 98, in get_merged_xform_survey
    children += element_list[0]["children"]