Unreleased blazy dependency leads to unusable site

Noted. Thank you.

Looks like the problem is the @RC, as also reported here:
💬 Unresolved dependency on DB update with latest rc version Fixed

AFAIK, requiring BETAs and RCs may need to correctly ask for the peak of the trees. In your case this will do:
composer require drupal/slick_views:^2.8

All dependencies will be in place up to Slick:2.10 an Blazy:2.17.
Notice, I did NOT declare @RC, or alike.
Machine like Composer is very smart to follow the declared dependencies. Human are not so, in this particular case, and may confuse Composer instead.

Also, perhaps the safest is to always use regular production directive "prefer-stable": true, in your composer.json.
Running the following will not download RCs, nor BETAs:
composer update --with-dependencies -n --prefer-dist

It will just stick the latest stable versions.

I don't think, it is a bug at all.
It works fine with the production mode above, or also fine with the correct require command.

Anything I missed to know?

Basically I agree with you that only stable versions should be used, but that's not always possible.

We had some problems which have been solved by 3367674 → and as far as I remember from my colleagues other strange things as well, that's why we decided to switch to @dev until 2.10 gets released instead of applying the patch from that issue.

Then yesterday we suddenly started getting the described errors which are fixed by #bfdf0d3 and even if that commit is included in the beta1 I decided to directly go to the RC1 as RC should be more stable than beta.

Got it.

Yes, depending on your composer setups, beyond me, you may want to use --prefer-source or --prefer-dist:

• https://git.drupalcode.org/project/blazy/-/blob/8.x-2.x/blazy.info.yml#L15
• https://stackoverflow.com/questions/16205100

To those in trouble, they won't work unless you configured your composer.json correctly to support the flags.
No need to hack the module info.yml file, etc.

Feel free to re-open if still an issue.

Thanks.

Automatically closed - issue fixed for 2 weeks with no activity.