Reactivity throws Svelte error: flush_sync_in_effect when upgrading from 5.35.0 to >=5.36.0 #17131
Description
Describe the bug
The 5.36.0 version throws Svelte error: flush_sync_in_effect when clicking the Open button, this is a unexpected regression.
Reproduction
Steps:
- Open the REPL
- Click on
Open - View console to see crash:
Svelte error: flush_sync_in_effect
Logs
Error
Svelte error: flush_sync_in_effect
Cannot use `flushSync` inside an effect
https://svelte.dev/e/flush_sync_in_effect
at flush_sync_in_effect (playground:output:462:18)
at flushSync (playground:output:2429:4)
at flush (playground:output:9902:3)
at setInitial (playground:output:11802:10)
at action (playground:output:9715:9)
at eval (playground:output:11630:8)
at $effect (playground:output:9573:5)
at update_reaction (playground:output:4178:57)
at update_effect (playground:output:4358:19)
at flush_queued_effects (playground:output:2520:6)System Info
-Severity
blocking an upgrade