Fix whois NPE on never connected user

Signed-off-by: Lixfel <agga-games@gmx.de>

src/de/steamwar/bungeecore/sql/SteamwarUser.java

@@ -329,7 +329,7 @@ public class SteamwarUser {
 
     public double getOnlinetime() {
         return getPlaytime.select(rs -> {
-            if(rs.next())
+            if(rs.next() && rs.getBigDecimal("Playtime") != null)
                 return rs.getBigDecimal("Playtime").doubleValue();
             return 0.0;
         }, id);