try {
  await client.rest.post(Routes.channelMessages(postId), {
    body: {
      // ...
    },
    files: files
  });
} catch (error) {
  // ??
}

try {
  await client.rest.post(Routes.channelMessages(postId), {
    body: {
      // ...
    },
    files: files
  });
} catch (error) {
  // ??
}

import { DiscordAPIError, RESTJSONErrorCodes } from "discord.js";

try {
} catch (err) {
  // Handle HTTP errors
  if (err instanceof DiscordAPIError) {
    // Handle here
  }

  // JSON error codes
  if (err.code === RESTJSONErrorCodes.Unauthorized) {
    // Handle here
  }
}

import { DiscordAPIError, RESTJSONErrorCodes } from "discord.js";

try {
} catch (err) {
  // Handle HTTP errors
  if (err instanceof DiscordAPIError) {
    // Handle here
  }

  // JSON error codes
  if (err.code === RESTJSONErrorCodes.Unauthorized) {
    // Handle here
  }
}

import { Client } from "@discordjs/core";

export class myClient extends Client {
  async myFunction(...) {
    if (!(this.isReady() || this.token))
    // The property "isReady" / "token" is not available for the "myClient" type.
  }
}

import { Client } from "@discordjs/core";

export class myClient extends Client {
  async myFunction(...) {
    if (!(this.isReady() || this.token))
    // The property "isReady" / "token" is not available for the "myClient" type.
  }
}

Please query the WHOIS server of the owning registrar identified in this output for information on how to contact the Registrant, Admin, or Tech contact of the queried domain name. 

Please query the WHOIS server of the owning registrar identified in this output for information on how to contact the Registrant, Admin, or Tech contact of the queried domain name.