fix(server/inventory): CanCarryItem returning false where an item should be able stack.

[gamenew09]

Fixes #1906

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Essentially when an inventory is full of items, when you try and check if you can add a stackable item that is in the inventory using CanCarryItem, it returns false. It seemed to stem from the strict metadata check.

When the metadata value is nil in CanCarryItem, the metadata table created is { type = nil }. Lua treats that new table as a hashmap even though it's really just an empty table (at least table.type looks at the table like that), and it seems to break the strict metadata check.

[gamenew09]

Hopefully I explained it well, my explaining skills are not the best haha

[jag3dagster]

The type value of metadata can be of any type, it doesn't have to be a string. I believe checking if metadata is not nil here is the better check