remove unnecessary logs, update upgrade cost after upgrading

src/classes/Guild.ts

@@ -17,6 +17,10 @@ export class Guild {
         this.level += 1;
         if (this.level > 7) {
             this.displayUpgradeCost = "Max level";
+        } else {
+            const newCost = this.getUpgradeCost();
+            if (newCost === null) return;
+            this.displayUpgradeCost = newCost;
         }
     }