How can I debug issues using an erlang lib?

Example in README says:

{ok, Connection} = lake:connect(host(), port(), <<"guest">>, <<"guest">>, <<"/">>)

So you need to use it like:

:lake.connect("localhost", 5672, "guest", "guest", "/")

And looking at the code - actually host can be both - binary or charlist, so all your approaches for the first argument have no effect on the result.