////CODE
const { ApplicationCommandOptionType, EmbedBuilder } = require('discord.js');

module.exports = {
    name: 'banner',
    description: '🧣 Search a user banner.',
    options: [
        {
            name: 'user',
            description: 'Provide the user to display.',
            type: ApplicationCommandOptionType.User,
            required: false
        }
    ],
    async execute(interaction, client) {
        const member = interaction.options.getUser('user');
        const user_banner = interaction.user.bannerURL();
        const member_banner = await client.users.fetch(member.id, { force: true });
        const member_banner_final = member_banner.bannerURL();

        if (interaction.user && user_banner) {
            const BannerEmbed = new EmbedBuilder()
            .setColor('#4D5656')
            .setDescription(`<@${interaction.user.id}> [banner](${user_banner})`)
            .setImage(user_banner)

            interaction.reply({ embeds: [BannerEmbed] })
        } else if (interaction.user && !user_banner) {
            const BannerEmbed = new EmbedBuilder()
            .setColor('#4D5656')
            .setDescription(`<@${interaction.user.id}> you don't have a banner but you have a colour displayed.`)
            .setImage(`https://singlecolorimage.com/get/${interaction.user.hexAccentColor}/400x100.png`)

            interaction.reply({ embeds: [BannerEmbed] })
        } else if(member && member_banner_final) {
            const BannerEmbed = new EmbedBuilder()
            .setColor('#4D5656')
            .setDescription(`<@${member.id}> [banner](${member_banner_final})`)
            .setImage(member_banner_final)

            interaction.reply({ embeds: [BannerEmbed] })
        } else if (member && !member_banner_final) {
            const BannerEmbed = new EmbedBuilder()
            .setColor('#4D5656')
            .setDescription(`<@${member.id}> doesn't have a banner but have a colour displayed.`)
            .setImage(`https://singlecolorimage.com/get/${member.hexAccentColor}/400x100.png`)

            interaction.reply({ embeds: [BannerEmbed] })
        } else {
            return;
        }   
    }
}



////////////////////////////////////ERROR
C:\Users\Marcos\Desktop\Core-Bot\Slash\Users\banner.js:17
        const member_banner = await client.users.fetch(member.id, { force: true });
                                                              ^

TypeError: Cannot read properties of null (reading 'id')
    at Object.execute (C:\Users\Marcos\Desktop\Core-Bot\Slash\Users\banner.js:17:63)
    at Object.execute (C:\Users\Marcos\Desktop\Core-Bot\Events\Message\interactionCreate.js:18:21)
    at Client.<anonymous> (C:\Users\Marcos\Desktop\Core-Bot\Handlers\eventsHandler.js:12:58)
    at Client.emit (node:events:525:35)
    at InteractionCreateAction.handle (C:\Users\Marcos\Desktop\Core-Bot\node_modules\discord.js\src\client\actions\InteractionCreate.js:81:12)
    at module.exports [as INTERACTION_CREATE] (C:\Users\Marcos\Desktop\Core-Bot\node_modules\discord.js\src\client\websocket\handlers\INTERACTION_CREATE.js:4:36)       
    at WebSocketManager.handlePacket (C:\Users\Marcos\Desktop\Core-Bot\node_modules\discord.js\src\client\websocket\WebSocketManager.js:352:31)
    at WebSocketShard.onPacket (C:\Users\Marcos\Desktop\Core-Bot\node_modules\discord.js\src\client\websocket\WebSocketShard.js:481:22)
    at WebSocketShard.onMessage (C:\Users\Marcos\Desktop\Core-Bot\node_modules\discord.js\src\client\websocket\WebSocketShard.js:321:10)
    at WebSocket.onMessage (C:\Users\Marcos\Desktop\Core-Bot\node_modules\ws\lib\event-target.js:199:18)

Node.js v18.7.0