Babel Polyfill loader for Azure Functions "only one instance of babel-polyfill is allowed"

babel.js

/**
 * Azure Functions can sometimes share a global scope to save memory (More than one function runs in the same interpreter).
 * When this occurs, babel will try to load twice. This is bad.
 * 
 * This file acts as a mediator to prevent it loading twice and always logs the result for my interest.
 * Inside my webpack.config.js, instead of 'babel-polyfill', I have 'src/polyfill/babel' (this file).
 */
if (global._babelPolyfill) {
    /* Polyfill is already loaded */
    if (console && console.warn) {
        console.warn('Babel Polyfill exits in this shared global scope. I will not load it.')
    }
} else {
    /* Polyfill is already loaded */
    if (console && console.warn) {
        console.warn('Babel Polyfill is not present in this shared global scope. Loading it.')
    }
    require('babel-polyfill')
}