And if they aren’t, good luck debugging it. I remember recently some typing issue in a webpack config where a correct key was marked as a type error in a presence of another construct, despite being documented and having an effect.

Also try exploring npm/telegraf classes (auto-documented) by looking at their type definitions. The whole bot api could have been written as simple repeated definitions, but someone chose the clever way of multi-level type mutations and derivatives.

Typescript will soon need secondary community-maintained type contracts that are human-readable and cross-checked with those in libraries. Something like @humane-types/*.