It is documented as illegal to use t.FailNow in a goroutine.
Uses of require assertions call t.FailNow. This may have led to
inconsistent test results as some assertions were subject to
undefined behavior. Note that it is still allowed to call
assert assertions in goroutines.
See: https://pkg.go.dev/testing#T.FailNow
Johan Brandhorst-Satzkorn
f2fa1142d3