Support propless SDCs

See core/modules/system/tests/modules/sdc_test/components/no-props/no-props.component.yml for an example of a propless SDC.

So yes, this is intended to work. And we should have an explicit test for it. 👍

Getting a test going.

Test exists now. And it fails as expected.

Note that the proposed resolution presents

Check if the component has props defined before trying resolving them.

as the only possible choice.

But there's another possible choice: storing an empty list of props even for propless component instances. It keeps the structure simpler and non-conditional. I think that would make future component upgrade paths simpler (e.g. for adding props to a component that is already in use — which 📌 Ensure querying JSON nested values when parent keys are unknown is possible in all supported databases Active is laying the groundwork for).

The cost of that simplicity is slightly more storage space being consumed, because there's additional JSON to be stored.

Thanks to the draft MR I pushed, with clear @todos, I think this is now actionable by novice contributors.

This is now blocking 📌 Create validation constraint for ComponentTreeStructure Needs work : https://git.drupalcode.org/project/experience_builder/-/merge_requests/1...

📌 Create validation constraint for ComponentTreeStructure Needs work is in, can you rebase this? 🙏

Doesn't need to be @Utkarsh_33 who works on this :)

It sounds like what is left for this issue is to get it to pass the tests.

With ~1 month of changes, I think a rebase is necessary.

Merged in upstream, looks like more tests than before are failing.