Installer WebUI Critical Error:
org.fedoraproject.Anaconda.Error: 'NoneType' object has no attribute 'path'


Reproducible: Didn't try

Steps to Reproduce:
1. Run the installer for Fedora 43 Beta 1.3
Actual Results:
The installer shows an "Installation failed" message with the above error.

Expected Results:
The installer should not produce an error.

Additional Information:
The drive chosen for the new installation has the following layout:
```
liveuser@localhost-live:~$ lsblk
NAME                                          MAJ:MIN RM   SIZE RO TYPE  MOUNTPOINTS
loop0                                           7:0    0   2,3G  1 loop  /run/install/sources/mount-0000-live_os_image
                                                                         /run/rootfsbase
sda                                             8:0    0   1,8T  0 disk  
└─sda1                                          8:1    0   1,8T  0 part  
sdb                                             8:16   1  14,5G  0 disk  
├─sdb1                                          8:17   1   2,6G  0 part  /run/initramfs/live
└─sdb2                                          8:18   1    30M  0 part  
zram0                                         251:0    0     8G  0 disk  [SWAP]
nvme0n1                                       259:0    0 953,9G  0 disk  
├─nvme0n1p1                                   259:1    0   487M  0 part  /mnt/sysroot/boot/efi
│                                                                        /mnt/sysimage/boot/efi
├─nvme0n1p3                                   259:2    0   1,5G  0 part  /mnt/sysroot/boot
│                                                                        /mnt/sysimage/boot
└─nvme0n1p2                                   259:3    0 951,9G  0 part  
  └─luks-0b6939a2-425f-48f1-8ad4-a25e2d8b62f6 252:0    0 951,9G  0 crypt /mnt/sysroot/var/tmp
                                                                         /mnt/sysroot/var/log
                                                                         /mnt/sysroot/var/cache
                                                                         /mnt/sysroot/srv
                                                                         /mnt/sysroot/home
                                                                         /mnt/sysroot
                                                                         /mnt/sysimage/var/tmp
                                                                         /mnt/sysimage/var/log
                                                                         /mnt/sysimage/var/cache
                                                                         /mnt/sysimage/srv
                                                                         /mnt/sysimage/home
                                                                         /mnt/sysimage
liveuser@localhost-live:~$ sudo btrfs subvolume list /mnt/sysroot
ID 257 gen 4322 top level 5 path @home
ID 265 gen 4329 top level 5 path @
ID 266 gen 4322 top level 5 path @srv
ID 267 gen 4325 top level 5 path @cache
ID 268 gen 4328 top level 5 path @tmp
ID 269 gen 4325 top level 5 path @log
```