Regression in 1.47.0 with empty default slots

[ekhaled]

This REPL fails with Cannot read property 'default' of undefined

but works in <= v1.46.0

The following ways of adding components in v1.47.0 work:

<Person :data :foo :bar />

<Person :data :foo :bar ></Person>

The following ways fail:

<Person :data :foo :bar >
</Person

<Person 
  :data 
  :foo 
  :bar
>
</Person>

[Conduitry]

It looks like there are a couple things going on here.

• Trying to send a default slot into a component that isn't set up to use it (by containing <slot/> somewhere in its definition) will result in that runtime error. This is also present in 1.46.0
• Whitespace-only content is treated as no content for the default slot in 1.46.0 but is treated as something to try to stick into the default slot in 1.46.1.

I'm not sure which of these is the best to address. Fixing the second one would restore 1.46.0 behavior. Is fixing the first one more desirable? Or might that be considered hiding an error, and we actually want an exception to be thrown in that case?

[ekhaled]

IMO if you send slot content into a component that does not have a <slot /> it should not throw an exception, maybe a dev warning

[Rich-Harris]

Fixed in 1.47.2, thanks. Opened a separate issue about slots in non-slottable components — #1020