The Portal Customization modal no longer hangs on a failed load

Opening the Portal Customization modal from the Portal page starts a request to load its current contents. If that request failed, the modal used to spin on its loading indicator forever, with no way to tell what had gone wrong and no way to close and retry short of reloading the whole admin page.

The failure could be worse than just a stuck spinner: clearing the loading state without an error meant the editor rendered on top of an empty contents object. That could read to you as though your customization had been wiped, and could throw an error in one of the editor's components once its first section was expanded, taking the whole Portal page behind the modal down with it.

What's fixed: a failed contents load now stops the editor from rendering at all and shows a clear error state instead, with a Try again button, or the option to close the modal and reopen it. Successful loads are unaffected.