Fix broken Container sorting
Fix broken Container sorting

- Container children without a position vector were causing non-deterministic sorting behavior.
- See: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/sort

> compareFunction(a, b) must always return the same value when given a specific pair of elements a and b as its two arguments. If inconsistent results are returned then the sort order is undefined

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