You can have data races in "safe" Go. If you race a trivial object [such as an integer] it's just radioactive and so long as you didn't need it to have any particular value (e.g. you were just going to write it to a log anyway, or you just discard it) you're fine. However if you race a non-trivial object then that's immediately Undefined Behaviour.

Of course Go programmers will say "Just don't do that" but that's exactly what C programmers told us about bounds misses, use after free and so on...