grimshot: fix branching on command exit status

The previous behavior was incorrect because `if` was checking the return
status of the `[` command which was never going to be an error. `[`
seems to only return an error if no args are provided. This was
basically a useless use of `[` anyway since it was just meant as a
straight interpretation of command exit, something that `if` can do
itself.

Compare:

```sh
[ ]; echo ?=$?
[ /bin/false ]; echo ?=$?
if [ /bin/false ]; then echo this is the unintended bug; fi
if /bin/false; then echo this will not be printed; fi
```

0 files changed, 0 insertions, 0 deletions