Fix discord bot loading

src/de/steamwar/bungeecore/BungeeCore.java

@@ -172,10 +172,12 @@ public class BungeeCore extends Plugin {
 
     @Override
     public void onDisable(){
-        try {
-            SteamwarDiscordBot.instance().getJda().shutdown();
-        } catch (Throwable e) {
-            getLogger().log(Level.SEVERE, "Could not shutdown discord bot", e);
+        if (SteamwarDiscordBotConfig.loaded) {
+            try {
+                SteamwarDiscordBot.instance().getJda().shutdown();
+            } catch (Throwable e) {
+                getLogger().log(Level.SEVERE, "Could not shutdown discord bot", e);
+            }
         }
 
         errorLogger.unregister();