no self challenge

src/slash/challenge.ts

@@ -25,6 +25,11 @@ export class ChallengeCommand implements SlashCommand {
 	async execute(int: CommandInteraction) {
         const args = createArgumentsObject<ChallengeArguments>(int.options.data);
         const client = int.client as CBClient;
+
+        if (int.user.id === args.opponent.id) return int.reply({
+            content: "You can't challenge yourself!",
+            ephemeral: true
+        });
         
         const player1 = await CBClient.findOrCreatePlayer(int.user.id);
         const player2 = await CBClient.findOrCreatePlayer(args.opponent.id);