Non-deterministic error is not printed

Reprex:

```r
bench::mark(if (runif(1) < 0.01) stop("stop"))
```
nothing is printed here...

Somewhat surprisingly, the  error is actually there, you can catch it:
```r
tryCatch(bench::mark(if (runif(1) < 0.01) stop("stop")), error = identity)
#> <simpleError in force(expr): stop>
```