Should check and warn if an action type is not annotated with ActionTypeAttribute

[dahlia]

It currently crashes without any warning or meaningful error message if an action type is not annotated with ActionTypeAttribute. This behavior can confuse library users whether they are aware that an action should be annotated with the attribute and just miss it or not aware of it at all.

• We should makeBlockchain<T> to throw a runtime exception (e.g., InvalidActionTypeException) with a well-guided error message if T is not annotated with the attribute.
• We could write a small Roslyn Analyzer so that this situation is warned at compile-time.

(Reported by @ipdae.)

[dahlia]

Since the patch #169, ActionTypeAttribute has been no more used by all IAction implementations, but only actions used with PolymorphicAction<T>. Currently, a MissingActionTypeException is thrown when an action type which lacks ActionTypeAttribute is passed to PolymorphicAction<T> class. This issue is not closed because we don't have a Roslyn Analyzer to detect this at compile-time.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. Thank you for your contributions.