This one is a dubious check. It catches some things, but has false positives; a simple one:

lib/event_broker/filters.ex:8:extra_range
The type specification has too many types for the function.

Function:
EventBroker.Filters.Trivial.filter/2

Extra type:
false

Success typing:
true

Against 0.30, this turns up a lot of errors, largely spurious; dialyzer infers a highly specific type and complains that our spec is more general. Leaning against.