May not return value in this else-if branch

test case:

```rconsole
> logical_abbr(quote(function(x=TRUE, na.rm = TRUE) FALSE ))
Error in if (logical_abbr(x[[i]])) return(TRUE) : 
  argument is of length zero
```
Merge pull request #571 from renkun-ken/patch-4

May not return value in this else-if branch