Source does not support feature count on MapServer layer

[iandees]

I get "INFO - Source does not support feature count" with this map, and I'm able to run a 1=1 query on it successfully.

dumper.py", line 169, in _find_oid_field_name
    for f in metadata['fields']:
KeyError: 'fields'

Originally posted by @Geremia in https://github.com/openaddresses/pyesridump/issues/75#issuecomment-1873047450