Optimized canReorderItems

[Connormiha]

This change replaces .slice() with a direct index-based loop to avoid unnecessary array allocations and improve performance.
It also adds a safety check to ensure both nodes exist in parent.body, preventing potential runtime errors when either node is not found.
Uses indexOf(..., fromIndex) to reduce lookup time for the second node.

Behavior remains unchanged for valid inputs, while the function now fails gracefully for invalid ones.

[willhoney7]

Hey! Thanks for submitting this. Can you explain why this is a helpful change? Like obviously if the indexOf returned -1 then it could be wrong, but was this actually happening to you in practice?

[Connormiha]

@willhoney7
The main change is that a new array is no longer created using slice, which in turn also reduces the workload for the garbage collector. I added the check for -1 to avoid a hypothetical situation where there’s an attempt to access a non-existent index.