Aren't go-routines the worst of all worlds? Sharp edges, undefined behavior galore? At least that was my takeaway when last using about 5 or 6 years ago. Did they fix go-routines in the meantime?
And then there's patently stupid design decisions like using raw slices as collections and the maybe-change-maybe-copy semantics of append() that don't make it easier to reason about shared data when it needs to be shared.