> Does it matter that it’s possible to misuse errors in Go if it virtually never happens? I just don’t find the point about what is possible interesting.
If you knew for sure that it virtually never happened, maybe not. But you don't. At best you know that a few particular individuals you're familiar with never mess it up (but then again, consider the people who "virtually never" write incorrect C). You can't trust random packages you haven't vetted, and you certainly can't trust code written by your junior software engineers.
> The other trade offs around readability, ergonomics, and so on seem more impactful.
Sum types have significantly better ergonomics. `(Result | null, Error | null)` takes four branches to handle properly, whereas `Either Result Error` takes two. And of course things get much worse once you're more than one layer deep, which in a language as procedural as Go you almost always are.
