Yeah just means you have to rely on linting and your ide to catch those errors. And hopefully the rest of your team does the same thing.

Tho I suppose if it is really important you can put an assert there but I'm not familiar with that wrt typescript, maybe the transpiler would kill that?

I've done the occasional type checking in that way in similar languages, it is kind of self documenting too. 90% of the time duck typing is what you want.