Typo in mapgen
Typo "defaut" in mapgen.lua, lines 146 and 149:
add_biome("grassy_dunes", nil, "defaut:sand", 1, "defaut:gravel", 3, nil, nil, nil, nil, nil, 5, 5, 50, 40, ethereal.grassy)
add_biome("grassy_ocean", nil, "defaut:sand", 2, "default:gravel", 1, nil, nil, nil, nil, nil, -310, 4, 50, 40, ethereal.grassy)
Correction could lead to chunk borders?