onError method
Called when an exception was occurred during the request.
Implementation
@override
void onError(DioException err, ErrorInterceptorHandler handler) async {
final errorMsg = (messageMapper(err) ?? '').trim();
if (err.requestOptions.extra['errorMessageFun'] != null) {
if (errorMsg.isNotEmpty) err.requestOptions.extra['errorMessageFun'](errorMsg);
}
handler.reject(err);
}