Thank you Simon, really appreciate you jumping in on this!

About the current issues

This one is currently number one error for us in crash collection system. Meaning not connected to Svelte, but out of everything. And in every case when I look at the code it should be impossible due to TypeScript checks.

Another one is connected to unowned signals. I was even asking about it during the Svelte Summit panel, but I think my question was misunderstood. The immediate problem we've had, I fixed by wrapping things into$effect.root to make them owned (never figured repro for our specific case). So there are no known problems in our codebase regarding this, but what makes me worried is if there are unknown or there will appear new, cause code is getting written. Also we are using classes and global state which sort of steers us towards unowned signals more.

The third one is the one where I can't provide even a reproduction. The only thing I know is the version from which it starts breaking and suspectthis PR to be the cause. Now awaiting some pending work to try and upgrade us again to see if maybe it was connected to something else that got fixed.

Also I just discovered that we are running half legacy mode even though we don't intend to. I try to follow issues and PRs quite closely to keep us updated and it never occurred to me that issues and fixes related to legacy mode could affect us. So now my intention is to force rune mode to reduce our bug surface area. I've tried it, but our code breaks due tostate_unsafe_mutation. Fortunately I was able tocontribute half of the fix myself and Paolo is of great helpfiguring out the second half!

This last one is what I am waiting right now to attempt upgrade us to see if maybe the third one is gone.

About your call offer

Mostly I think that would be helpful in cases where I can reproduce something in our codebase, but have zero success making a repro out of it. At least for me it works such that I can often guess what the source of the problem is by the description of a problem from my colleagues. So here I sort of think that even though there is no minimal repro you could make an educated guess based off your knowledge about internals. Definitely it was the case with Dominic and we had great success with couple of tricky bugs back in the day by just discussing it over the call and trying things.

Currently it seems like there is nothing like this, the question was more about if that's something that is available. Appreciate you offer and will contact you if it feels like that could help!

Also through our year of Svelte usage I noticed that you seem to rely on tests a lot. And the suite is definitely great. However sometimes new versions are getting released and they break stuff, but then the next version fixes other bugs. And we end up not being able to upgrade to get the later fixes.

The most difficult part about it is when when can't get a repro for the newly introduced bug and it's not like you can revert releases. In this cases it becomes a bit stressful. Not sure if anything could be done about that. Like maybe some RC process? But then again it'll slow things down. Anyway just wanted to share these thoughts.