null check for spawner owner in isAgitated() mixin

src/main/java/me/desht/pneumaticcraft/common/entity/semiblock/SpawnerAgitatorEntity.java

@@ -24,8 +24,6 @@
 import net.minecraft.world.level.Level;
 import net.minecraft.world.level.block.Blocks;
 
-import java.util.Objects;
-
 // Note: spawner agitator logic is handled by BaseSpawnerMixin for player-near checking,
 // and in MiscEventHandler#onMobSpawn() for tagging & mob persistence
 
@@ -40,7 +38,10 @@ public boolean canPlace(Direction facing) {
     }
 
     public static boolean isAgitated(BaseSpawner spawner) {
-        return Objects.requireNonNull(spawner.getOwner()).left()
+        if (spawner.getOwner() == null) {
+            return false;
+        }
+        return spawner.getOwner().left()
                 .map(be -> SemiblockTracker.getInstance().getSemiblock(be.getLevel(), be.getBlockPos()) instanceof SpawnerAgitatorEntity)
                 .orElse(false);
     }