Implement Centralized Custom Error Handling Logic.

[Mahadeb369]

The project currently relies on built-in error classes such as ValidationError and GraphQLError without a unified structure for handling or formatting errors.

Proposed Enhancement

Introduce a centralized custom error-handling mechanism to:

• Standardize error responses across all modules
• Improve debugging and client-side error parsing
• Ensure consistent use of error codes and messages

Benefits

• Easier maintenance and scalability
• Clearer and more predictable API responses
• Simplified client integration and error tracking

---

Steps to Reproduce

Below are examples of inconsistent error responses across different scenarios:

Failed Login

{
  "errors": [
    {
      "message": "GraphQlValidationError",
      "locations": [{ "line": 2, "column": 3 }],
      "path": ["tokenAuth"],
      "extensions": {
        "non_field_errors": [
          {
            "message": "No active account found with the given credentials",
            "code": "no_active_account"
          }
        ]
      }
    }
  ],
  "data": { "tokenAuth": null }
}

Failed Signup

{
  "errors": [
    {
      "message": "GraphQlValidationError",
      "locations": [{ "line": 2, "column": 3 }],
      "path": ["signUp"],
      "extensions": {
        "email": [
          {
            "message": "This field must be unique.",
            "code": "unique"
          }
        ]
      }
    }
  ],
  "data": { "signUp": null }
}

Invalid Access Token

{
  "detail": {
    "message": "Given token not valid for any token type",
    "code": "token_not_valid"
  },
  "code": {
    "message": "token_not_valid",
    "code": "token_not_valid"
  },
  "messages": [
    {
      "token_class": {
        "message": "AccessToken",
        "code": "token_not_valid"
      },
      "token_type": {
        "message": "access",
        "code": "token_not_valid"
      },
      "message": {
        "message": "Token is invalid or expired",
        "code": "token_not_valid"
      }
    }
  ],
  "is_error": true
}

---

System Info

Ubuntu 22.04 (x86_64)

Logs

No response

---

Validations

• Followed the [Code of Conduct](https://github.com/apptension/saas-boilerplate/blob/master/CODE_OF_CONDUCT.md)
• Reviewed the [Contributing Guidelines](https://github.com/apptension/saas-boilerplate/blob/master/CONTRIBUTING.md)
• Read the [documentation](https://docs.demo.saas.apptoku.com/)
• Verified that no duplicate issue exists
• Confirmed that this is a concrete bug (not a discussion topic)

[wang2-lat]

Consider adding error fingerprinting (hash-based deduplication) to track recurring issues in production. Tools like Sentry's grouping or custom error signatures help identify patterns across deployments. Also worth implementing structured logging alongside error codes—makes correlation between logs and API responses much easier when debugging distributed systems.