Use of uninitialized value in numeric ge (>=) and out of data in NBT.pm

[Tigahz]

When doing: perl generate-world --replace --postcode SO171BJ --size 1000 Highfield, I get the following error

Use of uninitialized value in numeric ge (>=) at C:/Users/User/Desktop/geocraft-master/lib/Minecraft/NBT.pm line 56, <DATA> line 309798. out of data at C:/Users/User/Desktop/geocraft-master/lib/Minecraft/NBT.pm line 56, <DATA> line 309798. Minecraft::NBT::get(Minecraft::NBT=HASH(0x20b6490), 1) called at C:/Users/User/Desktop/geocraft-master/lib/Minecraft/NBT.pm line 84 Minecraft::NBT::byte(Minecraft::NBT=HASH(0x20b6490)) called at C:/Users/User/Desktop/geocraft-master/lib/Minecraft/NBT.pm line 100 Minecraft::NBT::tag(Minecraft::NBT=HASH(0x20b6490)) called at C:/Users/User/Desktop/geocraft-master/lib/Minecraft/NBT.pm line 43 Minecraft::NBT::from_string("Minecraft::NBT", undef) called at C:/Users/User/Desktop/geocraft-master/lib/Minecraft/World.pm line 163 Minecraft::World::read_level(Minecraft::World=HASH(0x20ab530)) called at C:/Users/User/Desktop/geocraft-master/lib/Minecraft/World.pm line 23 Minecraft::World::new("Minecraft::World", "C:/Users/User/Desktop/geocraft-master/saves/Highfield", HASH(0x5875f28)) called at C:/Users/User/Desktop/geocraft-master/lib/Minecraft.pm line 34 Minecraft::world(Minecraft=HASH(0x1aa868), "Highfield", "init_chunk", CODE(0x59ddba0)) called at generate-world line 142

Any ideas on how to fix?