datawidget: Add check if tiddler exists for $filter attribute to avoide rsod

[pmario]

This PR fixes

• [BUG] when the $filter attribute returns non-existent tiddlers, the $data widget gives RSOD #8330

It adds the same if (tiddler) check, that is used for the $tiddler attribute.

@btheado please check the preview, once it is built

[vercel]

The latest updates on your projects. Learn more about Vercel for Git ↗︎

Name	Status	Preview	Updated (UTC)
tiddlywiki5	✅ Ready (Inspect)	Visit Preview	Jul 3, 2024 11:12am

[btheado]

Thanks @pmario it does fix the RSOD. I wonder if the behavior of <$data $filter="MissingTiddler1 MissingTiddler2"/> should be more similar to <$data title="MissingTiddler1"/> <$data title="MissingTiddler2"/>.

With your implementation the result is [], but it seems more consistent to me if it returns [ { "title": "MissingTiddler1" }, { "title": "MissingTiddler2" } ]

Probably that is debatable, but either way, we should have test cases to document the expected behavior.

[pmario]

Both $tiddler=missing and $filter=missing show the same result now. So I think that is consistent

[btheado]

Both $tiddler=missing and $filter=missing show the same result

Thanks for pointing that out. That changes my perspective. I agree those two should be consistent with each other.

[Jermolene]

Thanks @pmario @btheado