Steam Doesn't Open

When attempting to `flatpak run com.valve.software.Steam` I get this error printed in my console:

`
INFO:root:https://github.com/flathub/com.valvesoftware.Steam/wiki
INFO:root:Will set XDG dirs prefix to /home/sonny/.var/app/com.valvesoftware.Steam
Traceback (most recent call last):
File "/app/bin/steam", line 8, in
sys.exit(main())
^^^^^^
File "/app/lib/python3.11/site-packages/steam_wrapper.py", line 487, in main
should_restart += migrate_data(current_info, xdg_dirs_prefix)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/app/lib/python3.11/site-packages/steam_wrapper.py", line 334, in migrate_data
ignore = _get_host_xdg_mounts("xdg-data", flatpak_info)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/app/lib/python3.11/site-packages/steam_wrapper.py", line 305, in _get_host_xdg_mounts
dirs.add(os.path.join(*path_seq[1:]))
^^^^^^^^^^^^^^^^^^^^^^^^^^^
TypeError: join() missing 1 required positional argument: 'a'
`

Steam Version: Steam Client Beta as of January 17th, 2024
OS: Arch Linux x86_64
Flatpak Version: 1.15.6

Start by reproducing `flatpak run com.valve.software.Steam` on the reported Arch Linux and Flatpak versions. Read `/app/lib/python3.11/site-packages/steam_wrapper.py`, especially `_get_host_xdg_mounts` and its call from `migrate_data`, using the traceback as the entry point. Done means Steam launches without the reported `TypeError` during data migration.

Written by the indexing model from the issue text.