json.decoder.JSONDecodeError: Expecting value: line 1 column 1 (char 0)

[arthurlutz]

Trying to decode a protobuf message using the page.proto from googleapis : https://github.com/googleapis/googleapis/

python main.py -t protobuf --base64 -nk --definitions ~/local/googleapis/google/cloud/dialogflow/cx/v3/page.proto  ~/tmp/404ctf/protobuf.data  
Traceback (most recent call last):
  File "/home/arthur/local/ProtoDeep/main.py", line 3, in <module>
    main()
  File "/home/arthur/local/ProtoDeep/protodeep/protodeep.py", line 13, in main
    parse_and_run()
  File "/home/arthur/local/ProtoDeep/protodeep/cli.py", line 39, in parse_and_run
    process_args(args)
  File "/home/arthur/local/ProtoDeep/protodeep/cli.py", line 43, in process_args
    analyze(
  File "/home/arthur/local/ProtoDeep/protodeep/modules/analyze.py", line 63, in main
    definitions = json.loads(raw_defs)
                  ^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/json/__init__.py", line 346, in loads
    return _default_decoder.decode(s)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/json/decoder.py", line 337, in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/json/decoder.py", line 355, in raw_decode
    raise JSONDecodeError("Expecting value", s, err.value) from None
json.decoder.JSONDecodeError: Expecting value: line 1 column 1 (char 0)

the protobuf.data content is :

CJO2yQEIpLbJAQipncoBCOHZygEIlaHLAQiFoM0BCOLszQEIkofOAQiG1cwiGPTJzQEY1d3NARiY9c0BGNiGzgE=

(part of a CTF, not real data)