[AssetMapper] Asset Mapper fail after deleting "assets" folder

[Xbirdfr]

Symfony version(s) affected

7.*

Description

After compiling assets, if we delete the original assets folder (I don't want it on prod), symfony crash with :

An exception has been thrown during the rendering of a template ("The asset mapper directory "assets/" does not exist.").

{% block importmap %}{{ importmap('app') }}{% endblock %}

How to reproduce

• Setup a new symfony project
• create a controller to display a page
• compile assets
• check your application (it's works)
• delete the assets folder
• check your application (it's don't work anymore)

symfony new --webapp assetmappertest .
symfony console make:controller home
symfony console assets:install public
symfony console importmap:install
symfony console asset-map:compile

Possible Solution

No response

Additional Context

No response

[fracsi]

This also effects 6.4 as well. Currently you can use a simple workaround, just leave or create an empty assets directory.

[Xbirdfr]

assets folders + assets/controllers are needed at least (put a .empty do the trick)

[rynhndrcksn]

It looks like this error is thrown from AssetMapperRepository.php, specifically line 164.

I've verified the following check fixes this, I'm unsure if it's the solution that the core Symfony team would want though, or if they'd want a more thorough check (like if this condition is true and public/assets/ exists or something):

if ($_ENV['APP_ENV'] !== 'dev' && $path === 'assets/') {
    continue;
}

[nicolas-grekas]

I closed your PR a bit too quickly @rynhndrcksn, sorry about that. This cannot be the correct approach to me.
Maybe we could remove those exceptions in getDirectories? Or throw them only when $debug is on (the flag would be passed as a constructor argument).
WDYT @weaverryan?

[rynhndrcksn]

No problem @nicolas-grekas ! I didn't know that hard coded values weren't okay, my apologies. I'll be happy to make the necessary changes once we get feedback from Ryan and make a new PR if that's okay!

[weaverryan]

Indeed, you should be able to delete assets/ if you've compiled everything. If that's not possible (obviously it's not yet!) we should make it possible! The exception exists to help users not do a typo and then have trouble figuring out what they did wrong. In the PR #53677, I would:

A) Add a new argument to AssetMapperRepository constructor: $strictMode = true.
B) Add a new abstract arg after this one - https://github.com/symfony/symfony/blob/7.1/src/Symfony/Bundle/FrameworkBundle/Resources/config/asset_mapper.php#L77 - called something like strict mode
C) Pass %kernel.debug% to this new argument here https://github.com/symfony/symfony/blob/7.1/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/FrameworkExtension.php#L1329
D) Finally, back in AssetMapperRepository, use $this->strictMode to determine if the exception should be thrown.

Cheers!

[rynhndrcksn]

Ah okay, that makes a lot of sense, thank you Ryan! I'll get these modifications made and pushed later today!