Svelte 5: each block with index causes error (works with svelte 4)

[amit13k]

Describe the bug

The following code examples (which work properly with svelte 4) produce errors with Svelte 5,

{#each ["a", "b"] as result, i (i)}
  <div>{result}</div>
{/each}

{#each ["a", "b"] as result, i (i)}
  <div>{i}</div>
{/each}

<!-- This (with only one element) doesn't produce any errors. -->
{#each ["a"] as result, i (i)}
  <div>{result}</div>
{/each}

Reproduction

Example 1 Svelte 5 REPL

Example 2 Svelte 5 REPL

Logs

No response

System Info

System:
    OS: macOS 14.2
    CPU: (12) arm64 Apple M2 Pro
    Memory: 213.45 MB / 16.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 21.2.0 - /opt/homebrew/bin/node
    Yarn: 1.22.21 - /opt/homebrew/bin/yarn
    npm: 6.14.16 - /opt/homebrew/bin/npm
    pnpm: 8.10.5 - /opt/homebrew/bin/pnpm
    bun: 1.0.3 - ~/.bun/bin/bun
  Browsers:
    Chrome: 119.0.6045.159
    Chrome Canary: 121.0.6145.0
    Safari: 17.2

Severity

annoyance

[AgarwalPragy]

Duplicate issues:
#9629
#9408

[brunnerh]

@AgarwalPragy One of those is this very issue, the other does not look like it has anything to do with this.

Though on #9408 it claims to be linked from this. Something bugged here?

Anyway, I explained the issue over there:

This is a dev mode only issue. The production build is exactly the same (the implemented fix turns it into an indexed each).

This is currently still falsely added in dev mode:

$.validate_each_keys(() => [1, 2, 3], (item) => {
  return $.get(i);
});

[AgarwalPragy]

My bad. Updated.

[brunnerh]

Issue of first REPL should now be fixed via #9641.

Issue of second REPL still exists. Somehow adding the key term changes how i is being treated:

- text.nodeValue = $.stringify(i);
+ /* Update */
+ $.text_effect(text, () => $.get(i));

...and while I was writing that #9644 has been created 😅