Svelte stores become stuck after unhandled exception in subscriber

[nhhollander]

Describe the bug

If any svelte store subscriber raises an un-handled exception, future calls to .set() on any store will not notify subscribers.

In file svelte/src/store/index.js:58 in function set():

At line 58 the run_queue flag is set to true if there are no pending entries in the subscription queue¹. After the queue has finished running, the queue is emptied by calling subscriber_queue.length = 0 at line 67. In the event that an un-handled exception is raised from one of the subscribers, the function exits without clearing subscriber_queue. These dangling items cause the check on line 58 to always return false, preventing the dispatch loop from running until the page is reloaded.

Reproduction

https://svelte.dev/repl/7521a9a8fc53451bbc1b229eb50dd587?version=4.2.16

Logs

No response

System Info

System:
  OS: Linux 6.8 Arch Linux
  CPU: (24) x64 AMD Ryzen 9 3900X 12-Core Processor
  Memory: 12.92 GB / 62.74 GB
  Container: Yes
  Shell: 5.9 - /bin/zsh
Binaries:
  Node: 21.7.1 - /usr/bin/node
  npm: 10.4.0 - ~/.npm/bin/npm
npmPackages:
  svelte: ^4.0.5 => 4.2.16

Severity

annoyance

Footnotes

1. This behavior was first introduced in 46c9dbe4. ↩

[Opisek]

Also experiencing this bug. The call to .set doesn't only not notify the subscribers, but it also prevents further execution of the function it is called in.

Minimum working example: repl (counter should go to 2 but it only goes to 1)