Addresses Copilot's round-12 review on #2035. Both halves are regressions
from my own round-10 rework, which replaced "expand a rewritten template
through the lenient expandUriTemplate" with a part-by-part assembly and so
lost two properties that implementation had for free. Reproduced on
c6fb6271:
previewUriTemplate("x://{v}", { v: "\ud800" }) => throws URIError
previewUriTemplate("x://{a,}", { a: "1" }) => "x://1"
The first is the worse one: the preview runs during render, so an escaping
throw unmounts the whole panel rather than disabling its button -- and an
unpaired surrogate is real input, since `encodeURIComponent` raises URIError
on one and a paste can deliver it. The panel already reports that case
properly through `tryExpandUriTemplate`; the display path now degrades to
the raw template instead of taking the panel down with it.
The second promised a URI the user could never send: `{a,}` is an invalid
template whose submission is refused, but `a` survives into the
expression's varspecs, so filling it previewed `x://1`. An invalid
expression is now left standing as written, which is what the rest of the
panel already says about it.
Tests for both, plus one asserting the valid expressions around an invalid
one still preview.
npm run ci passes.
Signed-off-by: cliffhall <cliff@futurescale.com>
6a345ae77c