BUG: TypeError: Cannot read property 'get' of undefined

(node:206) UnhandledPromiseRejectionWarning: TypeError: Cannot read property 'get' of undefined
(node:206) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag `--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 1)
(node:206) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.

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Code :
 client.on("guildMemberAdd", async member => {
    const cachedInvites = guildInvites.cache.get(member.guild.id);
    const newInvites = await member.guild.fetchInvites();
    guildInvites.set(member.guild.id, newInvites);

    try{
        const usedInvite = newInvites.cache.find(inv => cachedInvites.cache.get(inv.code).uses < inv.uses);
        const joinChannel = member.guild.channels.cache.get(channel => channel.id === "840700441712263168")
        if(joinChannel) {
            joinChannel.send(`**><:Discord:831221457555554366>**Welcome ${member}  to our server Fiery Foxes E-Sports.** 
 

><:emoji_101:831317753204965407>**We hope you enjoy your time with us.**


><:emoji_100:831317050550779914>**Please don't forget to read**  #guidelines

><:fiery:830542549843443713>**Invited by : ${usedInvite.inviter} **

><:_hf_:826503267479322727>**Member count : ${member.guild.memberCount}**`)
            joinChannel.send("https://media.discordapp.net/attachments/806649507067723777/843579501413269564/10_3EA7AB3.gif").catch(err => console.log(err))

        }
    }
    catch(err) {console.log(err);}
})