Ignore air and void blocks when serializing structure

Author: Swedz

src/main/java/aztech/modern_industrialization/machines/multiblocks/structure/MIStructureTemplateManager.java

@@ -56,6 +56,7 @@
 import net.minecraft.resources.ResourceLocation;
 import net.minecraft.util.FastBufferedInputStream;
 import net.minecraft.world.level.Level;
+import net.minecraft.world.level.block.Blocks;
 import net.minecraft.world.level.block.entity.BlockEntity;
 import net.minecraft.world.level.block.state.BlockState;
 import net.minecraft.world.level.levelgen.structure.BoundingBox;
@@ -138,6 +139,10 @@ public static FromWorldResult fromWorld(Level level, BlockPos controllerPos, Dir
         for (BlockPos pos : BlockPos.betweenClosed(minPos, maxPos)) {
             BlockState state = toTemplateState(level, pos, level.getBlockState(pos), controllerDirection);
 
+            if (state.isAir() || state.is(Blocks.STRUCTURE_VOID)) {
+                continue;
+            }
+
             CompoundTag blockTag = new CompoundTag();
 
             blockTag.put("pos", NbtUtils.writeBlockPos(toTemplatePos(controllerPos, controllerDirection, pos)));