record output fails if empty contacts

[pvgenuchten]

Description

a problem when contacts is empty

  File "/home/pycsw/pycsw/pycsw/ogc/api/records.py", line 828, in item
    response = record2json(record, self.config['server']['url'], collection, stac_item)
  File "/home/pycsw/pycsw/pycsw/ogc/api/records.py", line 1065, in record2json
    for cnt in json.loads(record.contacts):
  File "/usr/lib/python3.8/json/__init__.py", line 341, in loads
    raise TypeError(f'the JSON object must be str, bytes or bytearray, '
TypeError: the JSON object must be str, bytes or bytearray, not NoneType

add check to see if contacts in '' or none

Environment

• operating system: linux
• Python version: 3.7
• pycsw version: master