- When rendering in the Viewport, next_tile is sometimes called after a reset has been performed, but before new tiles were generated. In that case, the tile list would be invalid, causing Blender to crash randomly. - When generating new tiles, the TileManager would not clear the tile lists before re-generating them, leading to some tiles being skipped during viewport rendering. - When popping the next tile from a tile list, a reference to the just-deleted object would be returned, now the object is copied before deleting it.