Should `NA` be a valid value for subsetting

Currently we have

```r
> [1, 2, 3][c(1, NA, 2)]
[1] 1 NA 2
>
```

which is in agreement with R, but I am not so sure whether this is something that should be possible. Especially for developers this does not seem so nice, but I am also not so sure whether this is something one wants when working with the repl interactively.

I think for these types of questions it is also nice to just ask people, so I started a [poll on mastodon](https://mastodon.social/@sebffischer/112896823370285914) the only problem being that I have no followers 😅 , but let's see.