Miner unit bugfixes

core/src/mindustry/ai/types/MinerAI.java

@@ -39,6 +39,7 @@ public class MinerAI extends AIController{
             //core full of the target item, do nothing
             if(targetItem != null && core.acceptStack(targetItem, 1, unit) == 0){
                 unit.clearItem();
+                miner.mineTile(null);
                 return;
             }
 
@@ -63,6 +64,8 @@ public class MinerAI extends AIController{
                 }
             }
         }else{
+            miner.mineTile(null);
+
             if(unit.stack.amount == 0){
                 mining = true;
                 return;