Discord JS, my users are able to create unlimited ticket channels when they react to the emoji

Users are able to create unlimited ticket channels when they react on 🎫 this emoji, what part do I miss in my script so that users are only able to create one ticket until they close it again?

My bots ID below is: 701327880046510080

Any help would be appreciated! 🙂

bot.on('messageReactionAdd', async (reaction, user, channel) => {
        if(user.partial) await user.fetch();
        if(reaction.partial) await reaction.fetch();
        if(reaction.message.partial) await reaction.message.fetch();
        if(user.bot) return;
        
        let ticketid = await settings.get(`${reaction.message.guild.id}-ticket`);
        
        if(!ticketid) return;
        
        
        if(reaction.message.id == ticketid && reaction.emoji.name == '🎫') {
            reaction.users.remove(user);
            const ticketChannel = reaction.message.guild.channels.cache.find(chan => chan.name === `ticket-${user.username}`)
            if (ticketChannel) return;
            reaction.message.guild.channels.create(`ticket-${user.username}`, {
                parent: '701254271861260389',
                position: 1,
                permissionOverwrites: [
                    {
                        id: '701327880046510080',
                        allow: ["MANAGE_CHANNELS", "MANAGE_GUILD", "MANAGE_ROLES", "MANAGE_EMOJIS", "READ_MESSAGE_HISTORY", "MANAGE_MESSAGES", "SEND_MESSAGES", "VIEW_CHANNEL"]
                    },
                    {
                        id: user.id,
                        allow: ["SEND_MESSAGES", "VIEW_CHANNEL", "READ_MESSAGE_HISTORY"]
                    },
                    {
                        id: reaction.message.guild.roles.everyone,
                        deny: ["VIEW_CHANNEL"]
                    },
                    {
                        id: '306893721725829121',
                        allow: ["SEND_MESSAGES", "VIEW_CHANNEL", "READ_MESSAGE_HISTORY"]
                    }
                ],
                type: 'text'
            }).then(async channel => {
                EMBED STUFF ..irrelevant. <-ignore this
                send.react("🔒")
            })
        }
        if(reaction.emoji.name == '🔒'){
            if(!reaction.message.channel.name.includes("ticket-")) return;
            reaction.users.remove(user);
            
            reaction.message.channel.delete()
        }
    })

Answer

Add these lines to your code

bot.on('messageReactionAdd', async (reaction, user, channel) => {
        if(user.partial) await user.fetch();
        if(reaction.partial) await reaction.fetch();
        if(reaction.message.partial) await reaction.message.fetch();
        if(user.bot) return;
        
        let ticketid = await settings.get(`${reaction.message.guild.id}-ticket`);
        
        if(!ticketid) return;

// add below here        
        const existing = bot.channels.cache.find(c => c.name === `ticket-${user.username}`)

        if (existing) {
            return reaction.message.reply({
                content: `You already have a ticket open, please close it first before creating a new one. See the ${existing} channel`
            });
        }
// add above here

// rest of code