[danvk]

Thanks for the pointer, I hadn't run across ts-runtime-checks before. It does do something similar to what I propose in the post. The difference is that ts-runtime-checks is opt-in. If you want a type validated at runtime, you have to write `Assert<T>`. What I'm proposing is that _all_ types be validated at runtime.

opt-in makes sense if you want these checks in production. The appeal of a "check everything" debug mode is that you wouldn't have to modify your TS at all to use it.