intl-messageformat throwing warnings about svelte-i18n HOT 8 CLOSED

[!] Error: UMD and IIFE output formats are not supported for code-splitting builds.
Error: UMD and IIFE output formats are not supported for code-splitting builds.
    at error (C:\Users\Dev\Documents\shoguneko-dev\fanhunter-rogue\node_modules\rollup\dist\rollup.js:5365:30)
    at normalizeOutputOptions (C:\Users\Dev\Documents\shoguneko-dev\fanhunter-rogue\node_modules\rollup\dist\rollup.js:13726:13)
    at getOutputOptionsAndPluginDriver (C:\Users\Dev\Documents\shoguneko-dev\fanhunter-rogue\node_modules\rollup\dist\rollup.js:13513:32)
    at Object.write (C:\Users\Dev\Documents\shoguneko-dev\fanhunter-rogue\node_modules\rollup\dist\rollup.js:13586:63)
    at C:\Users\Dev\Documents\shoguneko-dev\fanhunter-rogue\node_modules\rollup\dist\rollup.js:17015:66
    at Array.map (<anonymous>)
    at C:\Users\Dev\Documents\shoguneko-dev\fanhunter-rogue\node_modules\rollup\dist\rollup.js:17015:45
    at processTicksAndRejections (internal/process/task_queues.js:93:5)

<script>
  import Router from "svelte-spa-router";
  import AppHeader from "./components/AppHeader.svelte";
  import routes from "./routes.js";
  import { init, register } from "svelte-i18n";

  register("en", () => import("./locales/en.json"));
  register("es", () => import("./locales/es.json"));

  init({
    fallbackLocale: "en",
    initialLocale: {
      navigator: true
    }
  });
</script>

<AppHeader />
<Router {routes} />

import svelte from "rollup-plugin-svelte";
import resolve from "rollup-plugin-node-resolve";
import commonjs from "rollup-plugin-commonjs";
import livereload from "rollup-plugin-livereload";
import json from "rollup-plugin-json";
import { terser } from "rollup-plugin-terser";
const svelteConfig = require("./svelte.config");

const production = !process.env.ROLLUP_WATCH;

export default {
  input: "src/main.js",
  output: {
    sourcemap: true,
    format: "iife",
    name: "app",
    file: "public/build/bundle.js"
  },
  moduleContext: id => {
    const thisAsWindowForModules = [
      "node_modules/intl-messageformat/lib/core.js",
      "node_modules/intl-messageformat/lib/compiler.js"
    ];

    if (thisAsWindowForModules.some(id_ => id.trimRight().endsWith(id_))) {
      return "window";
    }
  },
  plugins: [
    svelte({
      // enable run-time checks when not in production
      dev: !production,
      ...svelteConfig
    }),

    // If you have external dependencies installed from
    // npm, you'll most likely need these plugins. In
    // some cases you'll need additional configuration �
    // consult the documentation for details:
    // https://github.com/rollup/rollup-plugin-commonjs
    resolve({
      browser: true,
      dedupe: importee =>
        importee === "svelte" || importee.startsWith("svelte/")
    }),
    commonjs(),

    json({
      // for tree-shaking, properties will be declared as
      // variables, using either `var` or `const`
      preferConst: true
    }),

    // In dev mode, call `npm run start` once
    // the bundle has been generated
    !production && serve(),

    // Watch the `public` directory and refresh the
    // browser on changes when not in production
    !production && livereload("public"),

    // If we're building for production (npm run build
    // instead of npm run dev), minify
    production && terser()
  ],
  watch: {
    clearScreen: false
  }
};

function serve() {
  let started = false;

  return {
    writeBundle() {
      if (!started) {
        started = true;

        require("child_process").spawn("npm", ["run", "start", "--", "--dev"], {
          stdio: ["ignore", "inherit", "inherit"],
          shell: true
        });
      }
    }
  };
}

//svelte.config.sj
//const sveltePreprocess = require('svelte-preprocess');
//
//module.exports = {
//    // we'll extract any component CSS out into
//    // a separate file � better for performance
//    css: css => {
//        css.write('public/build/bundle.css');
//    },
//    preprocess: sveltePreprocess()
//};

      "node_modules/intl-messageformat/lib/compiler.js"