jsonschema.exceptions.ValidationError: Could not parse json

Since I installed version 0.8.0 on my Mint 20, I got this error when I try to use Silkaj:

$ silkaj id poka
Traceback (most recent call last):
  File "/home/poka/.local/lib/python3.8/site-packages/duniterpy/api/client.py", line 89, in parse_response
    data = json.loads(response)
  File "/usr/lib/python3.8/json/__init__.py", line 357, in loads
    return _default_decoder.decode(s)
  File "/usr/lib/python3.8/json/decoder.py", line 337, in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
  File "/usr/lib/python3.8/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 above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/home/poka/.local/bin/silkaj", line 8, in <module>
    sys.exit(cli())
  File "/home/poka/.local/lib/python3.8/site-packages/click/core.py", line 829, in __call__
    return self.main(*args, **kwargs)
  File "/home/poka/.local/lib/python3.8/site-packages/click/core.py", line 782, in main
    rv = self.invoke(ctx)
  File "/home/poka/.local/lib/python3.8/site-packages/click/core.py", line 1259, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/home/poka/.local/lib/python3.8/site-packages/click/core.py", line 1066, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/home/poka/.local/lib/python3.8/site-packages/click/core.py", line 610, in invoke
    return callback(*args, **kwargs)
  File "/home/poka/.local/lib/python3.8/site-packages/silkaj/tools.py", line 53, in wrapper
    return loop.run_until_complete(f(*args, **kwargs))
  File "/usr/lib/python3.8/asyncio/base_events.py", line 616, in run_until_complete
    return future.result()
  File "/home/poka/.local/lib/python3.8/site-packages/silkaj/wot.py", line 182, in id_pubkey_correspondence
    pubkeys = await wot_lookup(id_pubkey)
  File "/home/poka/.local/lib/python3.8/site-packages/silkaj/wot.py", line 274, in wot_lookup
    results = await client(wot.lookup, identifier)
  File "/home/poka/.local/lib/python3.8/site-packages/duniterpy/api/client.py", line 455, in __call__
    return _function(self, *args, **kwargs)
  File "/home/poka/.local/lib/python3.8/site-packages/duniterpy/api/bma/wot.py", line 282, in lookup
    return client.get(MODULE + "/lookup/%s" % search, schema=LOOKUP_SCHEMA)
  File "/home/poka/.local/lib/python3.8/site-packages/duniterpy/api/client.py", line 372, in get
    return client.request_url(
  File "/home/poka/.local/lib/python3.8/site-packages/duniterpy/api/client.py", line 285, in request_url
    parse_response(content, schema)
  File "/home/poka/.local/lib/python3.8/site-packages/duniterpy/api/client.py", line 94, in parse_response
    raise jsonschema.ValidationError(
jsonschema.exceptions.ValidationError: Could not parse json : Expecting value: line 1 column 1 (char 0)

Maybe it's due to my environment, but I don't understand what's wrong.