Dir mode sometimes gives wrong total size

**Describe the bug**
Dir more (`-R`) sometimes gives the wrong total size for directories. It takes the size of largest directory instead of the total size.

### Example
```
> prn /home/user/ -s 200m -d 5 -l 2 -R
   2.94 GB │ /home/user/foo/bar/buzz
 731.26 MB │ /home/user/code/A/B/C
Found 2 directories with a total size of 2.94 GB
```

Expected total size of 3.67 GB