Save unit variables in processors

core/src/mindustry/entities/comp/BuildingTetherComp.java

@@ -0,0 +1,22 @@
+package mindustry.entities.comp;
+
+import mindustry.annotations.Annotations.*;
+import mindustry.game.*;
+import mindustry.gen.*;
+import mindustry.type.*;
+
+/** A unit that depends on a building's existence; if that building is removed, it despawns. */
+@Component
+abstract class BuildingTetherComp implements Unitc{
+    @Import UnitType type;
+    @Import Team team;
+
+    public Building building;
+
+    @Override
+    public void update(){
+        if(building == null || !building.isValid() || building.team != team){
+            Call.unitDespawn(self());
+        }
+    }
+}