SequenceType / GeneratorType That Can Also Throw?

I'm in the process of learning Swift and as an exercise, I'm writing a wrapper around SQLite. As I was experimenting, I realized that for queries that return rows (like SELECT), I could implement the SequenceType / GeneratorType protocols so that I can return a set of data for each sqlite3_step that I perform.

In practice, sqlite3_step either returns a row or is done, but in theory, it could error out. I'm not doing anything crazy with SQLite. It's just a simple data store for me, so I'm not rewriting schemas on the fly or potentially ripping the database out from under itself, but the fact remains that IN THEORY sqlite3_step could fail.

The question then is, is there a proper way to handle errors in the SequenceType / GeneratorType pattern? GeneratorType's next method doesn't support a throws parameter and returning nil just dictates the end of a sequence. Would there be a good way to handle the error and propagate it up the chain?