Error Handling - Law4Devs

Exception Hierarchy

Law4DevsException (base)
├── NotFoundError       (404)
├── ValidationError     (400)
├── RateLimitError      (429)
└── ServerError         (5xx)

All exceptions implement Dart’s Exception interface and expose message and statusCode.

Catching Errors

import 'package:law4devs/law4devs.dart';

try {
  final fw = await client.frameworks.get('nonexistent');
} on NotFoundError catch (e) {
  print('404: ${e.message}');
} on ValidationError catch (e) {
  print('400: ${e.message}');
} on RateLimitError catch (e) {
  print('429: Rate limited — SDK retried automatically');
} on ServerError catch (e) {
  print('${e.statusCode}: ${e.message}');
} on Law4DevsException catch (e) {
  print('API error ${e.statusCode}: ${e.message}');
}

Retry Behavior

The SDK automatically retries 429 and 5xx responses with exponential backoff:

Attempt	Delay
1st retry	1 second
2nd retry	2 seconds
3rd retry	4 seconds

404 and 400 are thrown immediately without retrying.

Safe Get Pattern

Future<FrameworkDetail?> safeGet(Law4DevsClient client, String slug) async {
  try {
    return await client.frameworks.get(slug);
  } on NotFoundError {
    return null;
  }
}

final fw = await safeGet(client, 'unknown-slug');
if (fw != null) {
  print(fw.name);
}

Error Properties

Property	Type	Description
`message`	`String`	Error message from the API
`statusCode`	`int?`	HTTP status code