We need to have a think about how to deal with web assets on the error pages

The error page is a ErrorDocument , in the end instance of Document, which should load WebAsset already, every time new ErrorDocument/Document instance are made

This will pull the AssetRegistry from Container, which already load all required assets:

hm, issue I see is that Registry does not load an asset file for active template,
that normally happen at Dispatch:

What I can think, is to load registry file in the error.php explicitly:

$wa->getRegistry()->addRegistryFile('templates/blablatemplate/joomla.asset.json');

That may help to avoid such problem, what do you think?
It does not have performance issue, because file will be parsed only once and flagged as parsed in registry instance.

I also had in mind a helper methods, like:

// For template
$wa->getRegistry()->addTemplateFile('blabla-name', 'site');

// For component
$wa->getRegistry()->addComponentFile('blabla-name');

or, do it in ErrorDocument::render(), that maybe more nice

That may help to avoid such problem, what do you think?
It does not have performance issue, because file will be parsed only once and flagged as parsed in registry instance.

I thought about that but I couldn't actually see any code preventing it from being parsed a second time actually

but I couldn't actually see any code preventing it from being parsed a second time

ups, that actually a bug ?
it must be here:

but I see it missed check for if (!empty($this->dataFilesParsed[$path])),
I will prepare a pull request, maybe at the weekend

fun thing, the issue was already fixed in past, but because the path was hardcoded for the "site" it does not work for administrator

I have made pull #28636

ahh oops :) closing for the PR