Add a compiler warning for updating destructured state

[WDeenik]

Describe the problem

Recently got into Svelte 5 after playing around with it some years back. Love the runes and the clarity they give to your code. Also love that they can be used to have shared state that's properly typed in TS. I'm using this pattern in a new app I'm building:

// chatState.svelte.ts
const chatState $state({ messages: [] });

export default chatState

// Chat.svelte
import chatState from './chatState';

chatState.messages.push(chatState);

Which works marvelously! However, I noticed that initially I would be tempted to destructure the state to clean up my code a bit:

// Chat.svelte
import chatState from './chatState';

const { messages } = chatState;

messages.push(chatState);

Which obviously won't work if you know how runes work. I'm fine with not destructuring state like this; it doesn't make my code much messier down the line. However, I know me and my colleague devs are quite used to destructure objects. I'm afraid we might be writing code like this by accident every now and then, leading to weird issues as there are no clear signs this won't be working if you glance at the code initially.

Describe the proposed solution

There are already compiler warnings for non-reactive updates. It would be really nice to have similar errors for non-reactive updates caused by destructured state variables.

Importance

nice to have

[Ocean-OS]

This should work; since $state objects are deeply reactive, mutating messages should trigger any reactivity dependent on chatState.messages.
If you were to do something like this, however:

// chatState.svelte.js
export const chatState = $state({ messageCount: 0 });
// App.svelte
let { messageCount } = chatState;
messageCount++;

It wouldn't work since you're not mutating, you're reassigning a destructured value.

[Conduitry]

As noted, this should work. Please provide an example in the REPL of what you're saying people might expect to work but does not.