Application crash cases

[z80]

1. Simple scene tree traversal (see below) called for currently loaded scene which contains XR nodes is guaranteed to crash the application with 100% probability. Application does not survive a single call of this function. However, if XR nodes are removed from the scene, application never crashes.

func _traverse_tree( node: Node ret: Array ):
    ret.push_back( node )
    var qty: int = node.get_child_count()
    for i in range(qty):
        var ch: Node = node.get_child( i )
        _traverse_tree( ch, ret )

2. With no headset connected application crashes with some chance. On average it crashes every second launch but sometimes many times in a row. So far observed 8 consecutive crashes followed by 1 successful launch.

3. With headset and controllers connected application also crashes with some chance which depends on scene complexity.