jQuery is not defined error.

Hi I wanted to add Material Design to my project, just importing the mdb.min.js file would sometimes create an error $(...).materialSelect is not defined. I found following solution https://gist.github.com/PabloCamp0s/a22b810af012d6110e98cb7539e96484#file-material-design-bootstrap-js

After adding the .scss and .js file. npm run watch compiled all the asset successfully. But now when I open the page I get following error

Uncaught ReferenceError: jQuery is not defined
    <anonymous> jQuery
    js app.js:710
    __webpack_require__ app.js:2637
    <anonymous> material-design-bootstrap.js:4

my app.js file look like this

require('./bootstrap');

import './material-design-bootstrap.js'

my boostrap.js file looks like this

window._ = require('lodash');

try {
     window.Popper = require('popper.js').default;
     global.$ = global.jQuery = require('jquery');

     // require('bootstrap');
     require('jquery-smooth-scroll')
} catch (e) {}

require('overlayscrollbars');
require('../../vendor/almasaeed2010/adminlte/dist/js/adminlte');

import Vue from 'vue';

window.Vue = Vue;

export const bus = new Vue();
window.axios = require('axios');

window.axios.defaults.headers.common['X-Requested-With'] = 'XMLHttpRequest';

/**
 * We'll load the axios HTTP library which allows us to easily issue requests
 * to our Laravel back-end. This library automatically handles sending the
 * CSRF token as a header based on the value of the "XSRF" token cookie.
 */
let token = document.querySelector('meta[name="csrf-token"]');

if (token) {
    window.axios.defaults.headers.common['X-CSRF-TOKEN'] = token.content;
} else {
    console.error('CSRF token not found: https://laravel.com/docs/csrf#csrf-x-csrf-token');
}

I have already install jquery using npm install jquery

and I also tried adding following to the top of webpack.mix file

mix.autoload({
    jquery: ['$', 'window.jQuery']
});

but still get

jQuery is not defined error

I have spend 4hrs trying to find a solution but no luck, can someone please point out what I am missing or doing wrong.

Thank you Jaysheel