i am trying to recreate parts of skyfactory like silkworms and i have tried to do it but i can't get it to work properly

Code (Text):

1. on right click:
2.     if {Running} is equal to 1:
3.         if targeted block is oak leaves:
4.             if distance between targeted block and player is less than or equal to 5:
5.                 set {SilkStage::%targeted block's position%} to 1
6.  
7. on script load:
8.     while {Running} is equal to 1:
9.         wait 1 tick
10.         loop {SilkStage::*}:
11.             if {SilkStage::%loop-value%} is greater or equal to 500:
12.                 set block at loop-value to bedrock
13.                 delete {SilkStage::%loop-value%}
14.             else:
15.                 add 1 to {SilkStage::%loop-value%}

thanks for any help fixing it

 

why do i need the index?

 

but it's fine if it doesn't exist because then it just won't do anything i thought
also can you put changes in it?