could you check if there is an error?

[devout cradle]

to get the players inventory container you have to use player.getComponent().container
to get every item in the players inventory you have to do a for loop through each slot...

I'll provide some code to help you out

[chilly tartan]

I'd really like it, thank you

[chilly tartan]

.

[worn herald]

Documentation: https://learn.microsoft.com/en-us/minecraft/creator/scriptapi/minecraft/server/entityinventorycomponent?view=minecraft-bedrock-stable

[wooden spear]

//return the total amount of specified item the player have in their inventory
export function getTotalItem(player,itemId) {
    const inv = player.getComponent("inventory")?.container;
    if (!inv) return 0
    let count = 0;
    for (let slot=0;slot<inv.size;slot++) {
        const item = inv.getItem(slot);
        if (!item) continue;
        if (item.typeId===itemId)
        count += item.amount;
    }
    return count;
}

//check if they have 6 diamonds or more using the function above

if (getTotalItem(player,"minecraft:diamond") >= 6)
//do something