To recreate Place down any redstone power source (i used a cauldron) then place down a comparator facing away from said power source and place a command block into the comparators output with the command
/setblock (X Y Z) 0
that way it will destroy the power source then place an comparator with the input facing into the command block and place another command block at the comparators output and in the command into the command block
/setblock (X Y Z) 380 0 replace
when you power the rig the power source will be destroyed but a cauldron will not be placed when you access the second command block you will see it says That there is no item 380.