$effect Infinite Loop Error (effect_update_depth_exceeded)

[lilacbora]

Describe the bug

While developing with Svelte 5, an infinite loop occurred due to using $state inside $effect.
When clicking the button in the example, the console in the developer tools logs multiple times before throwing the 'effect_update_depth_exceeded' error.
The issue occurs when both No.1 and No.2 are present, but if either one is commented out, the infinite loop does not happen.
Is this a bug in Svelte 5?
If it's not a bug, I would like to understand why the reactivity of b is triggered, causing the infinite loop.

Reproduction

https://svelte.dev/playground/hello-world?version=5.20.4#H4sIAAAAAAAACn2RT2vDMAzFv4rQCk2gJGzH_IPddtplx3kUJ1YyM9cOsbJ1ZPnuw01DCyvzxejpZz2jN6GVB8IMn8gYB19uMAoiUppJxbjDVhvymL1OyN994IKAu_XVY98n_pMMB62Wnm7pjbNMlj1mWPhm0D2DkbYrBbIXWAkr2BCDhBI2niVT1ErjKc4Fr7360pu0ymAKPhmMVlGrLSmQHjwP2nbwc1HnOc6FDTM21LbUcBTFUFYwBUmwbiMZr4XgNIWF2o-9kkx7RT2_7-nYEKkVqhOtoPzjP-cAaQrPLrm_JpOAQQkCmTwLzM_Qwwo1znpnKDGui7Z312d7-vpNCHgYCf5nbgyaw3XaSJEuMVTCFvXI7CyEdEuBSyUQnG2Mbj7K6byxEE6wnefqRR56Q0W6sJWwuEOmI2N2At7mX9OVV5JUAgAA

Logs

System Info

svelte 5.20
sveltejs/kit 2.17.0
sveltestrap 7.1.0

Severity

annoyance

[trueadm]

This is because the effect is both reading and setting b.id, so it will keep firing itself. You can wrap the read inside an untrack to prevent this behaviour.

[paoloricciuti]

Yeah, I think we can close this, not much we can do here...thanks for reporting tho!