InvalidToken exceptions in the schema validator are not caught

[jrconlin]

They should be caught as they were.

InvalidToken: 
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...
  File "marshmallow/schema.py", line 767, in _invoke_load_processors
    data=data, many=many, original_data=original_data)
  File "marshmallow/schema.py", line 865, in _invoke_processors
    data = utils.if_none(processor(data), data)
  File "autopush/web/validation.py", line 195, in extract_subscription
    ckey_header=d["ckey_header"],
  File "autopush/settings.py", line 335, in parse_endpoint
    token = self.fernet.decrypt(repad(token).encode('utf8'))
  File "cryptography/fernet.py", line 143, in decrypt
    raise InvalidToken