[empath-nirvana]

I think it's a reasonable complaint and I think that there should be some "strict" annotation that forces python to do that type checking before running the code, which should be completely backwards compatible.

Let's think of this in a deploy environment like kubernetes -- if you don't have such a check, then you could deploy code that fails _at runtime_, causing an outage, because someone made a mistake with types.

If you fail _at startup_, then the deploy will never go healthy and will fail, leaving the old pods still running, causing no interruption in service.

And yes you _should_ have this check in CI, but there's no reason not to have defense in depth.