fix: Fixed a bug where the select registry wasn't initialized.

Author: seailz

src/main/java/com/seailz/jdaframework/DiscordBot.java

@@ -47,6 +47,7 @@ public DiscordBot(String token) {
         builder = JDABuilder.createDefault(token);
 
         buttonRegistry = new HashMap<>();
+        selectRegistry = new HashMap<>();
 
         registerListeners(
                 new MessageContextMenuListener(),