Use eventual assertion in contract watcher test

[rmulhol]

hopefully resolves #100

[i-norden]

The more I think about this err the more confused I get... Everything in this test should be synchronous, so the err = t.Init() should block until processing is complete and we shouldn't need to wait for anything... I must be missing something.

[rmulhol]

Yeah, good point. I was thinking that some of the polling functionality depends on network calls that could have some inbuilt goroutines, but it's especially confusing that the error we're seeing appears to derive from missing database stuff that's put there before Init is called. Wondering if the BeforeEach/AfterEach stuff might be putting us in a race condition? Weird that it was consistently happening with basically just this test 🤔

[rmulhol]

Closing because it doesn't seem like this should fix the error. Hopefully additional logging from #145 will assist future debugging.