But if you are wondering about Error cases, they are there to see when you're looking for them because that ? while unobtrusive is something you can look for.

I'm sure in most IDEs you could have it highlight ? in a "Looking for error handling" mode if that's what you want.

Note that Rust does not consider control flow to be something the core language owns exclusively, you can return core::ops::ControlFlow to say actually I also have an opinion about whether you should keep going, this can make sense for a closure or function intended to be called inside an iterator or other loop context. Some of the ergonomics for this aren't finished, but what is there is already useful where a Result would work but is ugly because your early exit scenario isn't in fact an error at all.

Error handling is no less important than the happy-path.

You just did prove my point though which is that this is the only argument that Go programmers consider, and they blindly reject that adding more lines of code can harm readability.

Can we lower the rhetorical temperature a notch? Just because someone disagrees with you doesn't mean they're "blindly rejecting" your reasoning. In particular, I'm not just a Go programmer--I've used Java, C#, Python, JS, C++, and C in various professional over the course of my career and I've also played around with dozens of other languages and I have more experience with several of those languages than I have with Go. My opinions are shaped by those other languages at least as much as they're shaped by Go, and indeed I didn't start out having these "pro-Go" opinions--rather, I adopted them over time after allowing my preconceptions to be challenged. Note also that some of my preconceptions haven't changed--I still think sum types and enforced handling of return values are a good idea, for example.