Improve error message when a schema is not JSON valid.

[dgarros]

This PR aim to improve the error message reported by the SDK when the schema received from the server is not JSON valid.

Currently a json.decoder.JSONDecodeError exception will be raised but it doesn't contain enough information

2025-03-21T13:56:10.519447Z [error    ] Failed to execute generator: Expecting value: line 1 column 1 (char 0) [prefect.flow_runs] routing_key=check.generator.run
[...]
  File "/opt/infrahub/git/182ed5b8-d9c2-e54a-3ee3-106550e9b385/commits/f42cdfbfa634e470425650887aa4acf70cbc9ec2/infrahub_edge/models.py", line 2639, in get_and_save_infrahub_node
    node = await client.get(kind=kind, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/source/community/python_sdk/infrahub_sdk/client.py", line 467, in get
    schema = await self.schema.get(kind=kind, branch=branch)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/source/community/python_sdk/infrahub_sdk/schema/__init__.py", line 190, in get
    self.cache[branch] = await self.fetch(branch=branch, timeout=timeout)
                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/source/community/python_sdk/infrahub_sdk/schema/__init__.py", line 405, in fetch
    data: MutableMapping[str, Any] = response.json()
                                     ^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/httpx/_models.py", line 766, in json
    return jsonlib.loads(self.content, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/json/__init__.py", line 346, in loads
    return _default_decoder.decode(s)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/json/decoder.py", line 338, in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/json/decoder.py", line 356, in raw_decode
    raise JSONDecodeError("Expecting value", s, err.value) from None
json.decoder.JSONDecodeError: Expecting value: line 1 column 1 (char 0)

[codecov]

Codecov Report

Attention: Patch coverage is 60.00000% with 2 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
infrahub_sdk/schema/__init__.py	60.00%	2 Missing ⚠️

@@            Coverage Diff             @@
##           stable     #343      +/-   ##
==========================================
- Coverage   72.45%   72.44%   -0.02%     
==========================================
  Files          91       91              
  Lines        8165     8169       +4     
  Branches     1572     1572              
==========================================
+ Hits         5916     5918       +2     
- Misses       1838     1840       +2     
  Partials      411      411              

Flag	Coverage Δ
integration-tests	22.27% <40.00%> (+<0.01%)	⬆️
python-3.10	46.55% <40.00%> (-0.02%)	⬇️
python-3.11	46.55% <40.00%> (-0.02%)	⬇️
python-3.12	46.52% <40.00%> (-0.02%)	⬇️
python-3.13	46.52% <40.00%> (-0.04%)	⬇️
python-3.9	44.90% <40.00%> (+0.01%)	⬆️
python-filler-3.12	25.08% <20.00%> (-0.01%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
infrahub_sdk/schema/__init__.py	69.81% <60.00%> (-0.26%)	⬇️

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.