fix race condition when adding multiple vspace blocks
fix race condition when adding multiple vspace blocks

i5o/turtleblocksjs,hemantkasat/turtleblocksjs,Daksh/turtleblocksjs,tradzik/turtleblocksjs,Daksh/turtleblocksjs,i5o/turtleblocksjs,hemantkasat/turtleblocksjs,rodibot/turtleblocksjs,tradzik/turtleblocksjs,rodibot/turtleblocksjs,Daksh/turtleblocksjs,garyservin/turtleblocksjs,rodibot/turtleblocksjs,hemantkasat/turtleblocksjs,walterbender/turtleblocksjs,walterbender/turtleblocksjs,tradzik/turtleblocksjs,walterbender/turtleblocksjs,garyservin/turtleblocksjs,garyservin/turtleblocksjs,i5o/turtleblocksjs