Fixed crash when user tries to add existing hostname

app/add.js

@@ -47,12 +47,12 @@ module.exports = async (req, res) => {
 	}
 	
 	// Check if new peer already exists
+	const domain = `${new_hostname}.${user.name}.${env.TLD}`
 	if (user.peers.map((peer) => peer.name).includes(new_hostname)) {
 		console.log(`Host already exists for ${domain}`)
 		return res.sendStatus(409)
 	}
 	
-	const domain = `${new_hostname}.${user.name}.${env.TLD}`
 	
 	// Find next available host part
 	const used_ipv4_hosts = user.peers