It's a fixable problem. The attraction of Typescript was that all javascript is valid typescript. Great feature in the past years where people were migrating from one to the other. But now that most projects start out on typescript (honestly, if you are not you are doing it wrong) and never write a single line of Javascript, it's becoming an anti feature. The whole point of typescript is that we want to get away from that madness rather than stay close to it.

It already has a strict mode; it's time for an even stricter mode that simply cuts loose from javascript and flat out removes access to all the little compromises with strong typing that exist only because of javascript. It's a compilation target and with WASM emerging, even that is not a long term certainty.

IMHO the difference between e.g. Kotlin and Typescript is becoming smaller and smaller. I do both. There's been a cross over of lots of nice language features from Kotlin and other languages to Typescript. But at this point, Kotlin is a still a lot cleaner/safer than Typescript even though both can transpile to javascript and it also has a bit nicer ergonomics in some areas. E.g. data classes, property and interface delegation, co-coutines, etc. are all things that would be highly useful in Typescript as well. Android developers seem to love these features. And as Kotlin transpiles to javascript, there's no question about whether or not that can be done because it's already been done.