fix(#82): handle errors responses with a single Error

[annuh]

Fixes #82

This PR improves handling HTTP 400 errors with a single Error.

Documentation PostNL API: https://docs.api.postnl.nl/#tag/Locations/paths/~1shipment~1v2_1~1locations~1nearest/get:

// Response 400
{
  "Date": "2019-08-24T14:15:22Z",
  "Error": {
    "ErrorCode": "3000",
    "ErrorDescription": "Request format is invalid"
  },
  "RequestId": "09fd61fe-0099-4349-b71d-dce5c2472be9"
}

[codecov]

Codecov Report

Merging #86 (292b3ae) into v2.0.x (91748ef) will not change coverage.
The diff coverage is 100.00%.

Additional details and impacted files

@@            Coverage Diff            @@
##             v2.0.x      #86   +/-   ##
=========================================
  Coverage     69.05%   69.05%           
- Complexity     2209     2210    +1     
=========================================
  Files           124      124           
  Lines          6427     6427           
=========================================
  Hits           4438     4438           
  Misses         1989     1989           

Files	Coverage Δ
...seProcessor/Rest/AbstractRestResponseProcessor.php	56.92% <100.00%> (+1.36%)	⬆️

... and 2 files with indirect coverage changes

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[firstred]

Thanks a lot!

[annuh]

Thanks for the quick review!
Is it possible to create a new release that contains this, and the other fixes? 🙂

[firstred]

Sure thing! Just checking the v1.4.x branch as well and see if both'll work on PHP 8.3. If everything is fine, I'll make a new release.