Fixed merging circles at the same time causing a crash

[OliBomby]

closes #19922

• Depends on Fixed 0 length merge being allowed #19982

We might want to make a new issue for the underlying issue? If there are two circles at the same time and both selected and then you remove the first circle (somehow without deleting the second circle aswell), then the game crashes. Not sure if this is intented because you currently cant cause this behaviour in the editor.

[bdach]

We might want to make a new issue for the underlying issue? If there are two circles at the same time and both selected and then you remove the first circle (somehow without deleting the second circle aswell), then the game crashes

This is probably (disclaimer: I haven't checked) a failure stemming from HitObjectOrderedSelectionContainer's custom comparer, which is causing CompositeDrawable.ChangeInternalChildDepth() to fail to find the blueprint because of the internal binary search failing to locate the element (as there are two elements with equal keys in this case). And yes it's probably something we want fixed in the long run.

[peppy]

Let's go with this..

[peppy]

Going to go with this as-is, tracking the weirdness of this fix at #20040.