Enchant diamond sword with list of variables

[Expel_]

I am trying to make a custom enchant skript. I am currently making a list of enchantments which i intend to then apply to a diamond sword. However it gives an error.

Code:

function enchantedItem(i: item) :: item:
    if {_i} is diamond sword:
        chance of 50%:
            add sharpness 10 to {_enchantments::*}
        chance of 50%:
            add flame 10 to {_enchantments::*}
        chance of 50%:
            add protection 10 to {_enchantments::*}
        
        set {_item} to {_item} of {_enchantments::*}
    return {_item}

set slot 25 of player's current inventory to enchantedItem(diamond sword)

Error:
https://gyazo.com/1a2833ec419a2d0b475c0a34cbabbd3b

Thanks. Expel.

 

[Practice]

First, set {_item} to the item input

set {_item} to {_i}

Then, enchant {_item}

enchant {_item} with {_enchantments::*}