Follow-up PR: Count no-shows (#3309)
* node/approval-voting: test for invalid validator index in assignments This commit adds a unit test to show that, currently, validator indexes greater than n_validators (or the length of the approvals bitvector) are counted in n_assignments. In the subsequent commit we will correct this behavior. * node/approval-voting: ignore invalid validator indexes in n_assignments This commit ignores any validator assignments whose index is beyond n_validators. Without this check, an improperly crafted assignment would be counted towards the approval. It still remains that n_assignments and count_no_shows inspect the number of validators and approvals, respectively. Ideally we would add greater safety around ensuring these two values cannot differ.