Fix OnItemMoved event when the last item of a stackable stack is move…

[Erza]

…d into another stack

Pull Request Prelude

• I have followed proper The Forgotten Server code styling.
• I have read and understood the contribution guidelines before making this PR.
• I am aware that this PR may be closed if the above-mentioned criteria are not fulfilled.

Changes Proposed

Followup to #3916
A crash would occur when moving, for example, a stack of a single gold coin into another stack of gold coins.
The crash would only occur when the last item of a stack was being moved, aka. the stack being destroyed.

Old output of this scenario:

New output of this scenario:

==========================
=== Player:onItemMoved ===
==========================
{
    ["toCylinder"] = userdata: 0x06b4fc80,
    ["fromCylinder"] = userdata: 0x06b4fc58,
    ["count"] = 5,
    ["toPosition"] = {
        ["y"] = 64,
        ["x"] = 65535,
        ["z"] = 0,
        ["stackpos"] = 0
    },
    ["item"] = {
        ["type"] = 100,
        ["itemid"] = 2148,
        ["uid"] = 65544,
        ["actionid"] = 0
    },
    ["fromPosition"] = {
        ["y"] = 66,
        ["x"] = 65535,
        ["z"] = 1,
        ["stackpos"] = 0
    }
}
==========================

Issues addressed:

[Znote]

Reproduced crash:

Applied this PR, crash fixed:

Ohh yeah, I'm rocking OTClient with Protocol 12 😎