IssueTracker

Component used: Room
Version used: 2.1.0-alpha06
Devices/Android versions reproduced on: Doesn't matter

Using a Single in a Dao makes Room generate a Single.fromCallable. The docs in Single.fromCallable say:

If the {@link Callable} throws an exception, the respective {@link Throwable} is
delivered to the downstream via {@link SingleObserver#onError(Throwable)},
except when the downstream has disposed this {@code Single} source.
In this latter case, the {@code Throwable} is delivered to the global error handler via
{@link RxJavaPlugins#onError(Throwable)} as an {@link io.reactivex.exceptions.UndeliverableException UndeliverableException}.

If we subscribe to a Single and dispose before it delivers the EmptyResultSetException, will cause the exception to be sent to the global error handler, which means it will crash.

I think this could be avoided by using Single.create and checking if the emitter still has observers before trying to emit the error.

Can't provide a sample because this is a timing issue.