Tweaks on top of #1775

Make new interface not have default methods, make `Shadow` body throw
and tiny style changes

src/main/java/carpet/mixins/ChestBlock_customStickyMixin.java

@@ -1,9 +1,9 @@
 package carpet.mixins;
 
-import carpet.fakes.BlockPistonBehaviourInterface;
 import org.spongepowered.asm.mixin.Mixin;
 
 import carpet.CarpetSettings;
+import carpet.fakes.BlockPistonBehaviourInterface;
 
 import net.minecraft.core.BlockPos;
 import net.minecraft.core.Direction;