Svelte ignores new `this` bindings regarding private class fields declared with `$state`

[Ocean-OS]

Describe the bug

Found this issue while working on #15673. Basically, if you have a function (or other thing that adds a new this binding without being a class) inside of a class method, Svelte will still wrap any private property access with $.get/$.set.
I feel like accessing private properties inside this scopes that aren't classes should probably be a syntax error, but if not, at least this should be fixed. I put in a check for this in the code for $state.invalidate, so it shouldn't be too hard to fix for everything else.

Reproduction

REPL link

Logs

System Info

N/A

Severity

annoyance