Suspend user page has a bug preventing parts of the page working

[trichoplax]

Describe the bug The page "Warn or suspend user" in the moderator tools has a JavaScript error showing in the developer console of the browser:

Uncaught TypeError: this.element is null
[co-design.js:291:17](https://cdn.jsdelivr.net/npm/@codidact/co-design@latest/js/co-design.js)

This appears to be breaking functionality on some parts of the page. For example, the community switcher does not respond when clicked.

To Reproduce Steps to reproduce the behavior:

1. As a moderator, go to a user's profile page.
2. Click on "Moderator Tools".
3. Click on "warn or suspend user".
4. See error in the developer console.
5. Click on the community switcher and see no response.

Expected behavior There should be no error in the developer console and the page functionality such as the community switcher should work as on any other page.

Additional context This was discovered during work on #767 but it is already present in the develop branch, so I'm adding it as a separate issue to avoid holding up the moderator tool improvements. Although other page functionality is broken, the main purpose of the page still works (the user can be warned or suspended).