feat: add fallback logic in error handling

[sckimynwa]

Summary

According to Google API Design Docs (http_mapping), it says below.

While proto3 messages have native JSON encoding, Google's API Platform uses a different error schema for Google's JSON HTTP APIs for backward compatibility reasons.

in order to support AIP Error Format with backward compatibility, i add a fallback logic in parsing errors.

Description

• when error in normal format(as-is backward-compatibility format). it works like before.
• but when error in aip format (without 'error' wrapping), all the fields are wrapped in 'error' properties

for example.

Before

{
  "code": 3,
  "grpc-code": "INVALID_ARGUMENT",
  "message": "required field",
  "details": [
    {
      "@type": "type.googleapis.com/google.rpc.BadRequest",
      "fieldViolations": [
        {
          "field": "container_id",
          "description": "required field"
        }
      ]
    }
  ]
}

After

{
  "error": {
    "code": 3,
    "grpc-code": "INVALID_ARGUMENT",
    "message": "required field",
    "details": [
      {
        "@type": "type.googleapis.com/google.rpc.BadRequest",
        "fieldViolations": [
          {
            "field": "container_id",
            "description": "required field"
          }
        ]
      }
    ]
  }
}

all test codes work as fine, and if you say ok to these changes, i will add test codes!!

Reference

• https://cloud.google.com/apis/design/errors#http_mapping

Fixes below.

• error json format assumes that object should includes 'error' fields #1303 🦕

Notes

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[alexander-fenster]

Thank you!