How is it possible that the Message's author is equivalent to null?

TypeError: Cannot read properties of null (reading 'id')
    at Object.execute (D:\bot\dist\events\messageDelete.js:12:28) 
    at DiscordClient.<anonymous> (D:\bot\dist\handlers\events.js:43:54)
    at DiscordClient.emit (node:events:513:28)   
    at MessageDeleteAction.handle (D:\bot\node_modules\discord.js\src\client\actions\MessageDelete.js:24:16)

TypeError: Cannot read properties of null (reading 'id')
    at Object.execute (D:\bot\dist\events\messageDelete.js:12:28) 
    at DiscordClient.<anonymous> (D:\bot\dist\handlers\events.js:43:54)
    at DiscordClient.emit (node:events:513:28)   
    at MessageDeleteAction.handle (D:\bot\node_modules\discord.js\src\client\actions\MessageDelete.js:24:16)

const discord_js_1 = require("discord.js");
const EmbedBuilder_1 = __importDefault(require("../structures/overwrite/EmbedBuilder"));
const event = {
    name: discord_js_1.Events.MessageDelete,
    once: false,
    async execute(client, message) {
        if (message.author.id == client.user.id) return;
                          ^

const discord_js_1 = require("discord.js");
const EmbedBuilder_1 = __importDefault(require("../structures/overwrite/EmbedBuilder"));
const event = {
    name: discord_js_1.Events.MessageDelete,
    once: false,
    async execute(client, message) {
        if (message.author.id == client.user.id) return;
                          ^

const event: BaseEvent = {
    name: Events.MessageDelete,
    once: false,
    async execute(client: Client, message: Message) {
        if (message.author.id == client.user.id) return;

const event: BaseEvent = {
    name: Events.MessageDelete,
    once: false,
    async execute(client: Client, message: Message) {
        if (message.author.id == client.user.id) return;