Can return value of `.jsify()` be non-nullable if receiver is non-nullable? about sdk

[dgreensp]

@srujzs Thanks. I hope this is fixed/improved in dart:js_interop itself, because adding it to my codebase has downsides (it has to be imported, and it subtly changes the behavior of a well-known method, which could be confusing, all to save one character); I decided against it for now. Whereas if it comes "for free," it is a nice improvement.

[srujzs]

I think you're right that jsify() can't return null if the input is non-nullable. There is a discussion about what to do with undefined values here: #54025 that may affect this in the future, but for now, you can indeed declare an extension method like that.