The problem with the `TestStateFullRound1` is that the state that we are observeing, `cs`, can advance to the next height before we query its data. Specifically, on line `388`, when we called `validatePrevote`, the `cs` State had already advanced to height 2, so querying that State for the votes of height 1 either yielded nil or an erroneous value. This change adds a `ensurePrevoteMatch` function that checks that the prevote occurred and checks that it is for the expected block at the same time. If this change looks reasonable I can just apply the same fix to all of the places where we perform `ensurePrevote` followed by `validatePrevote` to use this function instead.