Catching runtime warnings in production

[WaltzingPenguin]

Describe the problem

Svelte 5 introduced a fair number of warning that may be issued at runtime: binding_property_non_reactive, state_proxy_equality_mismatch, etc.. These are "warnings" in that the window doesn't crash, but they all indicate real errors and the application will not work as expected. There's currently no good way to capture these errors and send them to Sentry/Bugsnag/etc.

Describe the proposed solution

I would like to see either:

• A compiler option to upgrade all warnings to errors
• Some sort of hook/callback to be able to add additional custom behaviour

Importance

nice to have

[webJose]

In my mind, the ideal solution is for Svelte to always log to an ILogger object. Consumers of the library could call a setLogger() function with their implementation of the ILogger they want/need, and if none is set, the default ILogger would simply log to the console.

[paoloricciuti]

Currently warnings are only issued in dev mode if I'm not mistaken but I guess we could have some sort of option to allow them in prod too (and eventually we would log to some logger)