BC Break: use namespaced exceptions, not SPL ones (questionable?)

[alcohol]

Instead of using generic SPL exceptions, I think it would be better to use local namespace exceptions, specifically tailored for each use-case. This will make testing also easier/more robust. This change would not be backwards compatible however.

[nyamsprod]

Using SPL Exceptions is fine but I would agree that some exceptions your are throwing are strange. For Instance DataProvider::getAlpha2 only accept strings. So if I gave it an array I would expect an InvalidArgumentException to be thrown not a DomainException.

So re-arranging the exceptions thrown should be a good Idea :+1: . Adding more exception classes while the SPL Exception seem to cover all the library exceptions (AFAIK) seems strange to me.

[alcohol]

That is true to a certain extend. However, ambiguity arises if you let exceptions bubble up in your application. You cannot reliably assume that any DomainException or InvalidArgumentException was specifically thrown by this library or a specific method in this library. Whereas if the type of exception was more explicit and it was namespaced, you could.