Prevent username retrieval if user is not authenticated and fix variable naming in DiscordAppealMapper.

database/src/main/java/com/alttd/altitudeweb/database/web_db/forms/DiscordAppealMapper.java

@@ -11,7 +11,7 @@ public interface DiscordAppealMapper {
 
     @Insert("""
             INSERT INTO discord_appeals (uuid, discord_id, discord_username, reason, created_at, send_at, e_mail, assigned_to)
-            VALUES (#{uuid}, #{discord_id}, #{discord_username}, #{reason}, #{createdAt}, #{sendAt}, #{email}, #{assignedTo})
+            VALUES (#{uuid}, #{discordId}, #{discordUsername}, #{reason}, #{createdAt}, #{sendAt}, #{email}, #{assignedTo})
             """)
     void createDiscordAppeal(DiscordAppeal discordAppeal);