fix: make first time setup flawless

missilewars-plugin/src/main/java/de/butzlabben/missilewars/game/Arenas.java

@@ -42,7 +42,7 @@ public class Arenas {
         File folder = new File(Config.getArenaFolder());
         File[] files = folder.listFiles();
         if (files.length == 0) {
-            File defaultArena = new File(folder, "arena.yml");
+            File defaultArena = new File(folder, "arena0.yml");
             try {
                 defaultArena.createNewFile();
                 Serializer.serialize(defaultArena, new Arena());

missilewars-plugin/src/main/java/de/butzlabben/missilewars/wrapper/abstracts/Lobby.java

@@ -58,7 +58,7 @@ public class Lobby {
     private Area area = Area.defaultAreaAround(Bukkit.getWorlds().get(0).getSpawnLocation());
     @SerializedName("map_choose_procedure") private MapChooseProcedure mapChooseProcedure = MapChooseProcedure.FIRST;
     @SerializedName("possible_arenas") private List<String> possibleArenas = new ArrayList<String>() {{
-        add("arena");
+        add("arena0");
     }};
 
     @Setter private transient File file;