How can i make a stack of barrels disappear individually using array in BP class?

what is the value of the variable int that I want to add to the script?

I have made an array actor reference and added all the static mesh actors in the scene… the name “barrel 00” actually was I mistake but I went on with it… didn’t think it is going to be a problem… could it? is it possible that it cant read any value because of “00”?

also how can I check if the index in my array is actually valid?