Rails Webpacker SCRIPT5009: 'app' is undefined - IE11 issues - ruby-on-rails

Question

For some reason most of my JS work in IE11 and lower fails. No issues with Chrome, Firefox, and Edge.
I have in the application.html.slim file:
meta http-equiv='X-UA-Compatible" content="IE=edge'
I found this: github webpacker thread
So I went through and tried the following in my config > webpack > production.js:
if (environment.plugins.getIndex('UglifyJs') !== -1) {
const plugin = environment.plugins.get('UglifyJs');
plugin.options.uglifyOptions.ecma = 5;
}
environment.config.optimization.minimizer[0].options.uglifyOptions.ecma = undefined
environment.plugins.get("UglifyJs").options.uglifyOptions.ecma = 5
None of those worked. In the console I'm getting:
SCRIPT5009: 'app' is undefined
From my home page I have it set up:
= content_for :head do
= stylesheet_pack_tag 'styles/home'
= javascript_pack_tag 'home'
= javascript_include_tag "//maps.googleapis.com/maps/api/js?key=#{ENV['MAP_KEY']}"
= content_for :body do
.container
.row
#map-banner.banner[type"hidden" data-location=all_locations.to_json]
=render template: '/layouts/application'
javascript:
document.addEventListener('DOMContentLoaded', app.home);
Then in my javascript > packs > home.js
import { mapStyle } from './styles/mapStyle';
app.home = () => {
function init() {
setupSlider();
homeSlider();
startGoogleMap();
let tabs = document.querySelectorAll('a.tab');
for (let tab of tabs) {
tab.addEventListener('click', tabClicked);
}
document
.querySelector('#region-select_')
.addEventListener('change', selectClicked);
}
return init();
};
Current versions:
webpack 3.12.0
rails 5.2.2
yarn 1.17.3
bootstrap 4.3.1
When I checked in the Network on my tiny-slider.js it's returning a status code of 304 however its returning 200 in Chrome. Any idea why it's not compiling?

Answer 1

Leaving this here in case someone finds it useful. Updated config > webpack > environment.js with:
environment.loaders.get('babel').exclude = [];