node: sketch of debug node logic

internal/consensus/replay_test.go

@@ -1217,6 +1217,9 @@ func (bs *mockBlockStore) PruneBlocks(height int64) (uint64, error) {
 	bs.base = height
 	return pruned, nil
 }
+func (bs *mockBlockStore) Close() error {
+	return nil
+}
 
 //---------------------------------------
 // Test handshake/init chain