I need help fixing a dragon fight skript

[Jonathan]

So I am working on a skript for a dragon fight on the server I am developing on. I have gotten stuck on the 2 remaining errors, as I do not know how to change the code to fix it. Here is my code:

on load:
  set {dragonTimer} to 0

every 1 minute:
  add 1 to {dragonTimer}
  if {dragonTimer} is 60:
    set {dragonTimer} to 0
    spawn ender dragon at location 0, 65, 10000 in world "world"
    set last spawned ender dragon's max health to 1000
    set last spawned ender dragon's health to 1000

on damage of ender dragon:
  set {_damage} to damage
  add {_damage} to {damage.%damager%}

on death of ender dragon:
  set {topDamager} to 0
  set {topDamage} to 0
  loop all players:
    if {damage.%loop-player%} is greater than {topDamage}:
      set {topDamage} to {damage.%loop-player%}
      set {topDamager} to loop-player

  if {topDamager} is not 0:
    set {_players} to all players
    remove {_players::*} from {topDamager}
    set {_size} to size of {_players}
    set {_blazePowder} to 1

    loop {_size} times:
      set {_currentPlayer} to {_players::[_loop-number - 1]}
      set {_currentDamage} to {damage.%_currentPlayer%}
      set {item} to blaze powder named "&5Dragon Essence"
      enchant {item} with mending

      if loop-number is 1:
        give 4 of {item} to {_currentPlayer}
      else if loop-number is 2:
        give 3 of {item} to {_currentPlayer}
      else if loop-number is 3:
        give 2 of {item} to {_currentPlayer}
      else:
        give 1 of {item} to {_currentPlayer}

And here are the errors I am getting:

I would really appreciate some help.

Thanks,
Jonathan