if err == nil { // inverted return err }
It’s usually pretty obvious why: eg
if err == nil { // we can exit early because we don’t need to keep retrying
Works especially well in languages that can make assignments in if statements, e.g:
if foo = 42 { }
if !(err != nil) {
would be clearer, I think. Seems like it's the same but would color differently in my editor.