ParseSelector return unknown in its return type instead of always using the fallback type when using TS 5.4

[stof]

See fregante/delegate-it#50 (and fregante/delegate-it#51 which runs the testsuite with typescript 5.4).
See also ed964d1#r139690533 where the discussion started.

To me, the change in the querySelectorAll type in that commit should not exist. It is a workaround for the fact that ParseSelector now returns unknown while it should never do it.
My intuition is that ExpandAnd is the one not properly handling the fallback.

[g-plane]

You can try ParseSelector<':is(a,)'> which is an invalid selector, and it returns Element.

[stof]

The case where this happens is not when having a known selector in ParseSelector but when defining a generic function (i.e. the same case than querySelectorAll in your commit, or in delegate-it)

[stof]

i.e. a case where we don't know whether we will have to use the fallback or a parsed type, but having both branches of the union.

[stof]

see https://www.typescriptlang.org/play?#code/JYWwDg9gTgLgBDAnmApnA3nACgQygZxQGUUAbFAYxmjgF84AzKCEOAciVQBMBaARwCuKKIh6FyVaAHoweQlDYAoRQwEA7KsAhq4XMigDmOGCgA8JCdShwUADxNqu+OPhhRgagwBo4AFQCi5CAoavB2Dk5wgSjBoXAAvNhyxPqSUOapVj4AEr4AsgAy0bEwAHwAFOKUVgBccBbV0ACUGMq0QA

ParseSelector<Selector, HTMLElement> does not satisfy Element

[fregante]

It worked, thank you!

fregante/delegate-it#51