setCustomKey method requires Object parameter, then asserts specific types

[dJani97]

I ran into a runtime error, caused by an assert in firebase_crashlytic's API:

firebase_crashlytics.dart#L204:

/// The value can only be a type [int], [num], [String] or [bool].
Future<void> setCustomKey(String key, Object value) async {
  assert(value is int || value is num || value is String || value is bool);
  return _delegate.setCustomKey(key, value.toString());
}

Effectively the only thing this method does with Object value is calling .toString() on it.

toString() is implemented in Object, so any Object passed to this method must inherit or override it. Is the assert really necessary?