Svelte 5: accessing state members from a class constructor bypasses reactivity

[robertadamsonsmith]

Describe the bug

When state member variables are initialised from a class constructor, they bypass reactivity logic as an optimisation (presumably).

However, this means that if other code is added directly to the constructor that asynchronously modifies state member variables (through this.), it does so in a way that bypasses reactivity logic.

This can by avoided by moving all logic to a member function in which reactivity logic is not bypassed, but it is not expected that this is required.

Either a fix to allow the expected behaviour, a runtime warning, or documenting the behaviour would be helpful.

Reproduction

https://svelte-5-preview.vercel.app/#H4sIAAAAAAAACpVR22qDQBD9lem2UAXR0EcTUwKlX1DIQ7eQZR2bpeuuOGNCEf-966apee2LyzlzLsM4isZYJFG-j8KpFkUpdl0nMsHf3QzohJYxYPJDr2dmQ7o3HW-lk6ytIoKdVX0L40xIbowzdMQaKnggVoxJoyxhur6MtXfE_aDZ9wmbFtPoiyPJRfHikdwjw9n3XxmQcRpB-7YLO9ZgHHs48NFQfn-tyU_KDni4JhDyW0j1AydJWm2j9maj0IwZxN71be0-1NECoy24OPmTBn66PEWxTMYr9d_maIqB8WORQcUrVuDwfLlo8rRarWb1plhO7saoW6KfQYrXX3AnBZQB75Vh4z7zPJdiCv-u9bVpDNainNeYPqYfoTtYofYBAAA=

Logs

No response

System Info

Svelte 5 Preview REPL

Severity

annoyance

[aradalvand]

Just encountered the exact same issue.