Fix ETA message

Signed-off-by: yoyosource <yoyosource@nidido.de>

BauSystem_Main/src/de/steamwar/bausystem/features/slaves/laufbau/states/LaufbauState.java

@@ -35,6 +35,7 @@ public interface LaufbauState {
     void next();
 
     default String eta(Player p, long start, int done, int total) {
+        if (done == 0) return "";
         return new SimpleDateFormat(BauSystem.MESSAGE.parse("TIME", p)).format(Date.from(Instant.ofEpochMilli((System.currentTimeMillis() - start) / done * total)));
     }
 }