cuelang.org: removing the final tag from a search widget's predefined set of tags re-adds the whole set

[jpluscplusm]

What page were you looking at?

https://cuelang.org/examples/shortcodes/search/ (after https://cuelang.org/cl/1203609 gets submitted)

What version of the site were you looking at?

cue-lang/cuelang.org@130e790

What did you do?

I used the search widget's "Tags" drop-down to remove both predefined tags.

What did you expect?

The search widget would remain unscoped, with no tags present.

What did you see instead?

The page reloaded, re-adding all the predefined tags.

Additional info

This was flagged during review of the PR that added predefined tags, and is being tracked (i.e. not fixed during implementation) because it's such a niche corner case: cue-lang/cuelang.org#477 (review).

If this issue has affected your use of the cuelang.org site, please add a comment to this issue explaining how it affected you so that we can re-prioritise this issue.