- When there's an error stat'ing the output directory flux now prints
the error:
Before:
```
✗ invalid output path ./ro-dir/foo
```
After:
```
✗ invalid output path "./ro-dir/foo": stat ./ro-dir/foo: permission denied
```
- When no output directory is provided flux now explicitly says so in
the error:
Before:
```
✗ invalid output path
```
After:
```
✗ output path cannot be empty
```
Signed-off-by: Max Jonas Werner <mail@makk.es>
6700aac4a4