Description of problem:
There will be wrong message occurring when entering wrong Target path with some letters

Version-Release number of selected component (if applicable):
cockpit-machines-238.2-1.el8.noarch
libvirt-dbus-1.3.0-2.module+el8.3.0+6423+e4cb6418.x86_64

How reproducible:
100%

Steps to Reproduce:
1. Click "Storage pools"

2. Click "Create storage pool", enter wrong Target path with some letters, like : test

Actual results:
There will be error message bellow the Target path, saying like:

Error opening directory '/run/user/0/tes': No such file or directory

Expected results:
The error message may need some correction.

Additional info: