Public signup page breaks if password policy and email verification are enabled

Issue Summary

In Jira Core 8.12 onwards, the AUI was upgraded to version 9, as can be verified on Preparing for Jira 8.12.

This change broke the Service Desk account signup when public signup is allowed, if a Password Policy is enabled and if Email Verification is required for signups.

Steps to Reproduce

1. Install Jira Core 8.12 and Jira Service Desk 4.12
2. Enable public signup on Jira by going to Cog > Applications > Jira Service Desk Configuration
3. Enable the Email Verification for new signups – this requires a working outgoing mail server
4. Go to Cog > System > Password Policy and enable a password policy (e.g Secure
5. Try creating a new account by opening an Incognito window and navigating to <BASE-URL>/servicedesk/customer/user/signup

Expected Results

You should be able to create new customer accounts.

Actual Results

The window is blank:

In the browser console the error below can be observed:

batch.js?locale=en-US:1627 Uncaught Invariant Violation: Minified React error #200; visit https://reactjs.org/docs/error-decoder.html?invariant=200 for the full message or use the non-minified dev environment for full errors and additional helpful warnings. 

Workaround

Disable either:

1. A password policy enforcement or
2. Disable email verification requirement for new accounts