fix(gotrue): handle empty error response

Author: Vinzent03

packages/gotrue/lib/src/fetch.dart

@@ -45,27 +45,38 @@ class GotrueFetch {
     if (error is! Response) {
       throw AuthRetryableFetchException(message: error.toString());
     }
+    final response = error;
 
     // If the status is 500 or above, it's likely a server error,
     // and can be retried.
-    if (error.statusCode >= 500) {
+    if (response.statusCode >= 500) {
       throw AuthRetryableFetchException(
-        message: error.body,
-        statusCode: error.statusCode.toString(),
+        message: response.body,
+        statusCode: response.statusCode.toString(),
       );
     }
 
     final dynamic data;
+
+    // Catch this case as trying to decode it will throw a misleading [FormatException]
+    if (response.body.isEmpty) {
+      throw AuthUnknownException(
+        message:
+            'Received an empty response with status code ${response.statusCode}',
+        originalError: response,
+      );
+    }
     try {
-      data = jsonDecode(error.body);
+      data = jsonDecode(response.body);
     } catch (error) {
       throw AuthUnknownException(
-          message: error.toString(), originalError: error);
+        message: 'Failed to decode error response',
+        originalError: error,
+      );
     }
-
     String? errorCode;
 
-    final responseApiVersion = ApiVersion.fromResponse(error);
+    final responseApiVersion = ApiVersion.fromResponse(response);
 
     if (responseApiVersion?.isSameOrAfter(ApiVersions.v20240101) ?? false) {
       errorCode = _getErrorCode(data, 'code');
@@ -85,21 +96,21 @@ class GotrueFetch {
               .isEmpty) {
         throw AuthWeakPasswordException(
           message: _getErrorMessage(data),
-          statusCode: error.statusCode.toString(),
+          statusCode: response.statusCode.toString(),
           reasons: List<String>.from(data['weak_password']['reasons']),
         );
       }
     } else if (errorCode == ErrorCode.weakPassword.code) {
       throw AuthWeakPasswordException(
         message: _getErrorMessage(data),
-        statusCode: error.statusCode.toString(),
+        statusCode: response.statusCode.toString(),
         reasons: List<String>.from(data['weak_password']?['reasons'] ?? []),
       );
     }
 
     throw AuthApiException(
       _getErrorMessage(data),
-      statusCode: error.statusCode.toString(),
+      statusCode: response.statusCode.toString(),
       code: errorCode,
     );
   }

packages/gotrue/lib/src/gotrue_client.dart

@@ -1006,8 +1006,8 @@ class GoTrueClient {
 
         return AuthResponse(session: session);
       }
-    } catch (error) {
-      notifyException(error);
+    } catch (error, stackTrace) {
+      notifyException(error, stackTrace);
       rethrow;
     }
   }

packages/gotrue/lib/src/types/auth_exception.dart

@@ -1,4 +1,5 @@
 import 'package:gotrue/src/types/error_code.dart';
+import 'package:http/http.dart' as http;
 
 class AuthException implements Exception {
   /// Human readable error message associated with the error.
@@ -46,24 +47,47 @@ class AuthSessionMissingException extends AuthException {
           message ?? 'Auth session missing!',
           statusCode: '400',
         );
+  @override
+  String toString() =>
+      'AuthSessionMissingException(message: $message, statusCode: $statusCode)';
 }
 
 class AuthRetryableFetchException extends AuthException {
   AuthRetryableFetchException({
     String message = 'AuthRetryableFetchException',
     super.statusCode,
   }) : super(message);
+
+  @override
+  String toString() =>
+      'AuthRetryableFetchException(message: $message, statusCode: $statusCode)';
 }
 
 class AuthApiException extends AuthException {
   AuthApiException(super.message, {super.statusCode, super.code});
+
+  @override
+  String toString() =>
+      'AuthApiException(message: $message, statusCode: $statusCode, code: $code)';
 }
 
 class AuthUnknownException extends AuthException {
+  /// May contain a non 2xx [http.Response] object or the original thrown error.
   final Object originalError;
 
-  AuthUnknownException({required String message, required this.originalError})
-      : super(message);
+  AuthUnknownException({
+    required String message,
+    required this.originalError,
+  }) : super(
+          message,
+          statusCode: originalError is http.Response
+              ? originalError.statusCode.toString()
+              : null,
+        );
+
+  @override
+  String toString() =>
+      'AuthUnknownException(message: $message, originalError: $originalError, statusCode: $statusCode)';
 }
 
 class AuthWeakPasswordException extends AuthException {
@@ -74,4 +98,8 @@ class AuthWeakPasswordException extends AuthException {
     required super.statusCode,
     required this.reasons,
   }) : super(message, code: ErrorCode.weakPassword.code);
+
+  @override
+  String toString() =>
+      'AuthWeakPasswordException(message: $message, statusCode: $statusCode, reasons: $reasons)';
 }

packages/gotrue/lib/src/types/auth_state.dart

@@ -13,6 +13,6 @@ class AuthState {
 
   @override
   String toString() {
-    return 'AuthState{event: $event, session: $session, fromBroadcast: $fromBroadcast}';
+    return 'AuthState(event: $event, session: $session, fromBroadcast: $fromBroadcast)';
   }
 }