In ReadExecutor, verify a statement execution returns a ResultSet

[jdegoes]

Currently, the boolean value returned from Statement#execute in ReadExecutor is ignored. It should be checked, and if false, it means there is no result set being returned, which we should handle appropriately rather than just calling getResultSet().

[TobiasPfeifer]

even SELECT NULL LIMIT 0; returns a ResultSet (empty). I couldn't figure out a way to get Statement#execute return false for a SELECT. And I don't think someone can sneak in an update into a Read[A] that gets reflected as having no ResultSet

However just to handle all corner cases I would suggest to return an empty result stream.

I'll give this a try