'Undefined Reference' when indexing a $bindable prop in dev mode

[jhwz]

Describe the bug

The generated code in dev mode references an undefined variable, maybe it thinks every variable in the expression has been declared with $.prop?

Reproduction

https://svelte.dev/playground/8e7f81107bbd4530a08a77ebe520a10b?version=5.28.2

Look at the JS output, compiler options must be:

• generate: client
• dev: true

Logs

System Info

NA

Severity

annoyance

[tanishq-aggarwal]

I discovered a bug that seems similar to this one.

Description

When destructuring a prop via $props() without supplying a default value, event handlers that reference that prop throw a ReferenceError at runtime—even though the console log immediately before shows the correct value. This behavior is non-intuitive and prevents the normal use of destructured props in runes mode.

Reproduction

https://svelte.dev/playground/70034561066340c98c157d86ec3c2df2?version=5.28.2
Child2 works as expected, but Child1 throws ReferenceError though it shouldn't.

[paoloricciuti]

Yup both of this should be fixed by my pr.