Sometimes there's an event and eth_getLogs returns
nothing.
Solution: trim the nulls from the topic filter's tail
It appears that in some implementations or setups
eth_getLogs topics: [A, null, null, null] won't return
logs when only [A] was there.
This patch is a quick workaround that trims nulls from
that said tail. A proper fix would likely require
an incursion into ethabi to make Topic optional.
c3c2461af3