Fix SchemElo NPE

src/de/steamwar/sql/SchemElo.java

@@ -38,6 +38,7 @@ public class SchemElo {
     private final int season;
 
     public static int getElo(SchematicNode node, int season) {
-        return select.select(node, season).elo;
+        SchemElo elo = select.select(node, season);
+        return elo != null ? elo.elo : 0;
     }
 }