TypeError: undefined is not a constructor (evaluating 'email.normalize('NFC')')

[rokoroku]

TypeError: undefined is not a constructor (evaluating 'email.normalize('NFC')')

Caused by calling str.normalize() in the isemail module

String.prototype.normalize() is not supported in every browsers.
Adding polyfill like unorm or just adding mock function returns itself fixes the issue.

[rokoroku]

Here's my simple workaround:

if (typeof String.prototype.normalize === 'undefined') {
  String.prototype.normalize = function () { return this; };
}