Crash when dragging a node

[hshapley]

When dragging a Node in ARSceneView 2.0.3, it can crash with the exception java.util.NoSuchElementException: Collection contains no element matching the predicate. This is because in Node.kt on line 873 (in onMove), it uses first instead of firstOrNull. If it used the latter, then the null check would work, but since it just uses first, it throws an exception instead. In PoseNode line 27, it uses firstOrNull, so no issue there. I'm also not sure whether the logic is correct for the predicate - checking it.node == parent seems a little strange. Wouldn't it be better to check it.node == this, or checking both conditions?