let directives with named slots are broken

[harshmandan]

Describe the bug

I am using let:directives to pass values down to components in named slots. It is working fine till the version 3.28.0.
Upgrading past that breaks the functionality with this error:

let:prop declared on parent component cannot be used inside named slot

Reproduction

Here's a REPL on version 3.28.0:

https://svelte.dev/repl/cf8a9290ad0547978399db0c6265522c?version=3.28.0

The same REPL on version 4.0.0:

https://svelte.dev/repl/cf8a9290ad0547978399db0c6265522c?version=4.0.0

Logs

No response

System Info

MacOS, Chrome v108

Severity

blocking an upgrade

[gtm-nayan]

This is an expected breaking change. #6049