anydate() crashes some R versions when passed a vector of length 0

Windows 11
{anytime} 0.3.11

The following work fine:
``` R
# R 4.1.3
anytime::anydate(integer())
anytime::anytime(integer())
# R 4.5.0
anytime::anytime(integer())
```

But this crashes R:
``` R
# R 4.5.0
anytime::anydate(integer())
```