_from_api_repr_scalar fails, if parameter value is None

[peku33]

Tested on latest (2.6.0) version, using python 3.8 on linux.

If ArrayQueryParameter contaning at least one None value is added to query_parameters, when using job.query_parameters (result after submitting the job) 'NoneType' object has no attribute 'mode' will be raised.

This is because:

• _from_api_repr_scalar is called on ArrayQueryParameter
• _QUERY_PARAMS_FROM_JSON[array_type](value, None) for value in values, the value is None
• this corresponds to _int_from_json(None, None)
• _not_null(None, None) is called
• return value is not None or field.mode != "NULLABLE" raises exception

Stack trace:

AttributeError: 'NoneType' object has no attribute 'mode'
  (snip)
  File "(snip)/site-packages/google/cloud/bigquery/job/query.py", line 632, in query_parameters
    return self._configuration.query_parameters
  File "(snip)/site-packages/google/cloud/bigquery/job/query.py", line 314, in query_parameters
    return _from_api_repr_query_parameters(prop)
  File "(snip)/site-packages/google/cloud/bigquery/job/query.py", line 79, in _from_api_repr_query_parameters
    return [_query_param_from_api_repr(mapping) for mapping in resource]
  File "(snip)/site-packages/google/cloud/bigquery/job/query.py", line 79, in <listcomp>
    return [_query_param_from_api_repr(mapping) for mapping in resource]
  File "(snip)/site-packages/google/cloud/bigquery/query.py", line 632, in _query_param_from_api_repr
    return klass.from_api_repr(resource)
  File "(snip)/site-packages/google/cloud/bigquery/query.py", line 257, in from_api_repr
    return cls._from_api_repr_scalar(resource)
  File "(snip)/site-packages/google/cloud/bigquery/query.py", line 239, in _from_api_repr_scalar
    converted = [
  File "(snip)/site-packages/google/cloud/bigquery/query.py", line 240, in <listcomp>
    _QUERY_PARAMS_FROM_JSON[array_type](value, None) for value in values
  File "(snip)/site-packages/google/cloud/bigquery/_helpers.py", line 48, in _int_from_json
    if _not_null(value, field):
  File "(snip)/site-packages/google/cloud/bigquery/_helpers.py", line 43, in _not_null
    return value is not None or field.mode != "NULLABLE"

[tswast]

Thanks for the report! This should be fixed in the next version.