change to (hopefully) prevent index out of bounds exception + return "-" when fromPercentage == 0

src/main/java/de/lunarakai/minecleaner/utils/MinecleanerStringUtil.java

@@ -30,6 +30,9 @@ public class MinecleanerStringUtil {
     }
 
     public static String percentageString(int whatPercentage, int fromPercentage) {
+        if(fromPercentage == 0) {
+            return "-";
+        }
         float percent = (float) whatPercentage/fromPercentage;
         percent = percent * 100;
         String percentageString = String.format("%.1f", percent);