referencing this when it is already the window object in SignUp

[gerwinbrunner]

Hi,

I get the following error

Exception in delivering result of invoking 'createUser': TypeError: _this7.showMessage is not a function
    at http://localhost:3010/packages/std_accounts-ui.js?hash=69063d010a3ed9c833c97bb301c6d32ad0e2425e:2400:20
    at http://localhost:3010/packages/accounts-base.js?hash=00b4c32478a678093a294cc73c7dbd8c59c65d48:324:26

I think this is due to the fact of using the this reference here

I use an extended class MyLoginForm extends LoginForm

[gerwinbrunner]

Changing this line to

    const SignUp = (_options) => {

fixes it for me