> while in parallel checking for type errors.
Why are you suggesting this not be done during development? Is it bc while ESBuild is fast and runs in parallel, it's still only as fast as the slowest parallelized task, and in this case the slowest task is checking for type errors? And I assume checking for type errors is the slowest because it has to invoke an external resource, tsc?
Would it not make sense to have two development bundlers then? One for getting your code up and running quickly, and a second that outputs a dummy build artifact, but allows a more thorough production-like build that includes type checking (or other long running activities)? That way you get all the verification you would like, but don't pay a price on waiting for your code to deploy?