Blokowanie teleportacji na bloki wyżej niż 128 w nether

Witam, posiadam skrypt na teleport do netheru. Niestety nie potrafie rozwiązać problemu tepania nad bedrock. Jeżeli ktoś postawi blok nad bedrockiem lub postawi blok na spawnie w netherze gracza tepa nad bedrock. Ktoś może pomóc?

on portal:
    event-entity is a player:
        cancel event
        if {netherloc::%player%} exist:
            wait 5 ticks
            teleport player to location of {netherloc::%player%}
            stop
        wait 5 ticks
        set {_block} to block at location at (random number between -2000 and 2000, 0, random number between -2000 and 2000) in world "world_nether"
        loop all blocks above {_block}:
            if loop-block is air:
                block below loop-block is not lava
                block below loop-block is not air
                block below loop-block is not bedrock
                if block above loop-block is air:
                    teleport player to loop-block
                    set {netherloc::%player%} to location of loop-block
on portal create:
    if player is in world "world_nether":
        cancel event