Error while running event Noxys_Trees::on_tick (ID 0)

Unknown tile name: alien-metal
stack traceback:
[C]: in function 'count_tiles_filtered'
__Noxys_Trees__/control.lua:747: in function 'spawn_trees'
__Noxys_Trees__/control.lua:793: in function 'process_chunk'
__Noxys_Trees__/control.lua:933: in function <__Noxys_Trees__/control.lua:878>

This always happens whenever I just increment the degradable tiles option.

Should be fixed in 0.5.2.

Thank you ^^ hope you're enjoying the space age expansion!

I have not yet actually had the time to play it.