Bootstrap doesnt handle JSON decode errors when reading the startup file

[Williangalvani]

Traceback (most recent call last):
  File "/main.py", line 22, in <module>
    bootstrapper.run()
  File "/bootstrap/bootstrap.py", line 236, in run
    for image in self.read_config_file():
  File "/bootstrap/bootstrap.py", line 62, in read_config_file
    config = json.load(config_file)
  File "/usr/lib/python3.7/json/__init__.py", line 296, in load
    parse_constant=parse_constant, object_pairs_hook=object_pairs_hook, **kw)
  File "/usr/lib/python3.7/json/__init__.py", line 348, in loads
    return _default_decoder.decode(s)
  File "/usr/lib/python3.7/json/decoder.py", line 337, in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
  File "/usr/lib/python3.7/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)

Reported by @NickNothom

[Williangalvani]

maybe we should have a broad except in here after all https://github.com/bluerobotics/BlueOS-docker/blob/master/bootstrap/bootstrap/bootstrap.py#L68

[Williangalvani]

fixed by #1459