Update `ChunkTag`, `AreaContainmentObject` and `ColorTag` tag param usage. (#2364)
* Update tag param usage for `ChunkTag`
Contributes to issue #2355.
* Update tag param usage for `AreaContainmentObject`
Contributes to issue #2355.
* Update tag param usage for `<ColorTag.mix[]>`
Contributes to issue #2355.
* Remove `null` checks in a few `AreaContainmentObject` tags.
New tag processing makes sure the parameter is valid as pointed out by @tal5!
* Remove `null` check in `<ColorTag.mix[]>`
(
commit: 16e64a5)
