Error thrown after tabbing to confirm password field.

Problem/Motivation

On the user add/edit user form, if the user has the permission "bypass password policies", an error is thrown after typing in the password field, then tabbing to the next element or shifting focus elsewhere in the browser.

TypeError: Argument 1 passed to Drupal\Core\Render\MainContent\AjaxRenderer::renderResponse() must be of the type array, null given, called in /var/www/build/html/core/lib/Drupal/Core/Form/FormAjaxResponseBuilder.php on line 89 in Drupal\Core\Render\MainContent\AjaxRenderer->renderResponse() (line 45 of /var/www/build/html/core/lib/Drupal/Core/Render/MainContent/AjaxRenderer.php).

This appears to happen because the ajax will trigger regardless of the permissions set, but the array it is expecting is only conditionally available provided the user does not have the "bypass password policies" permission.

The error can be seen from the JavaScript console on a browser, or if logging is enabled, it will also show up in the db logs on admin/reports/dblog.

Proposed resolution

Proposed resolution is attached as a patch file. Limit when the ajax event fires based on current user's permissions.

Remaining tasks

Needs review.

User interface changes

None.

API changes

None.

Data model changes

None.