Mutating array within $state rune breaks reactivity in certain cases

[biwecka]

Describe the bug

Given the following state variable let arr = $state<string[]>([]). When mutating it with arr.push("...") and arr.splice(i, 1) reactivity breaks after adding at least two items to the array and then removing all of them. Afterwards adding an item again does not update the UI.

Reproduction

This REPL contains an example of the potential bug and two alternatives to mutating the array which work as expected. The working alternatives both reassign the value of the array. That's why I'm unsure if the reactivity breaking when only using splice might actually be the the expected behavior.

Logs

No response

System Info

System:
    OS: Linux 6.1 NixOS 23.11 (Tapir) 23.11 (Tapir)
    CPU: (8) x64 11th Gen Intel(R) Core(TM) i5-1135G7 @ 2.40GHz
    Memory: 12.13 GB / 15.27 GB
    Container: Yes
    Shell: 5.9 - /run/current-system/sw/bin/zsh
  Binaries:
    Node: 20.9.0 - /etc/profiles/per-user/biwecka/bin/node
    npm: 10.1.0 - /etc/profiles/per-user/biwecka/bin/npm
  npmPackages:
    svelte: ^5.0.0-next.1 => 5.0.0-next.28

Severity

annoyance