"Invalid argument" when attempt is made to attach to the vim process

When I tried to attach to a vim process running in another terminal this was printed:

```
$ reptyr 49529
[-] Process 49529 shares a process group with 1 other processes. Unable to attach.

Unable to attach to pid 49529: Invalid argument
```

It looks like a bug that the "Invalid argument" message was printed.

FreeBSD 14.1
