bug#33294: xwidget-insert crashes Emacs

[Glenn Morris]

Stefan Monnier wrote:

> The "impossible" category is for when such objects can never be passed
> to `type-of`, typically because they are not available to Elisp.
>
> But there's no harm/risk to "allow" a particular kind of object even if
> it's actually impossible for it to be passed to type-of.

Pardon my ignorance, but why then is the fallback behaviour on getting
an "impossible" type to abort Emacs, rather than eg just throwing an
error or returning 'unknown or somesuch?