add comment and fix flake

physical/raft/raft.go

@@ -1461,6 +1461,16 @@ func (b *RaftBackend) StartRemovedChecker(ctx context.Context) {
 		for {
 			select {
 			case <-ticker.C:
+				// If the raft cluster has been torn down (which will happen on
+				// seal) the raft backend will be uninitialized. We want to exit
+				// the loop in that case. If the cluster unseals, we'll get a
+				// new backend setup and that will have its own removed checker.
+
+				// There is a ctx.Done() check below that will also exit, but
+				// in most (if not all) places we pass in context.Background()
+				// to this function. Checking initialization will prevent this
+				// loop from continuing to run after the raft backend is stopped
+				// regardless of the context.
 				if !b.Initialized() {
 					return
 				}

vault/external_tests/raftha/raft_ha_test.go

@@ -364,6 +364,9 @@ func TestRaftHACluster_Removed_ReAdd(t *testing.T) {
 			if !server.Healthy {
 				return fmt.Errorf("server %s is unhealthy", serverID)
 			}
+			if server.NodeType != "voter" {
+				return fmt.Errorf("server %s has type %s", serverID, server.NodeType)
+			}
 		}
 		return nil
 	})