onError method Null safety

void onError(
  1. DioError err,
  2. ErrorInterceptorHandler handler
)

The callback will be executed on error.

If you want to continue the error , call handler.next.

If you want to complete the response with some custom data directly, you can resolve a Response object with handler.resolve and other error interceptor(s) will be skipped.

If you want to complete the response with an error message directly, you can reject a DioError object with handler.reject, and other error interceptor(s) will be skipped.

Implementation

void onError(
  DioError err,
  ErrorInterceptorHandler handler,
) =>
    handler.next(err);