Caused by the Cycles-X merge.
The old style of tile rendering was removed, leaving the script to error
out trying to set the tile size.
Tile rendering came back in a new form (but only really relevant for
large resolution rendering), so now leave setting auto_tile & tile_size
alone (since previews are rendered at PREVIEW_RENDER_DEFAULT_HEIGHT 128
-- which should never make a difference here).
Maniphest Tasks: T91808
Differential Revision: https://developer.blender.org/D12937
690e1baf72