This plugin provides a method to check if all AsyncValue
variables from Riverpod are ready for consumption.
final valueA = ref.watch(providerA);
final valueB = ref.watch(providerB);
return AsyncValueSync.all(
[valueA, valueB],
data: (values) => values,
error: (values) => values, // the error callback is called if any `AsyncValue` has an error
loading: () => 'loading',
);