PyMOL 3.1.0a0 crashes when reading 3.0.0 session files

[pjmartel]

Describe the bug

Pymol Open Source 3.1.0a0 crashes when opening session files from Pymol 3.0.5 (paid version)

To Reproduce

Steps to reproduce the behavior:

1. Go to 'File - Open'
2. Select a .pse file from Pymol 3.0.5
3. Open it
4. The console prints "Reading session 3.0.0 file"
5. Pymol crashes

Expected behavior

I would expect it to open the session file and view it normally.

Environment

• PyMOL Version: 3.1.0a
• PyMOL Source: pymol-open-source
• Operating System: Windows 11

Additional context

Sessions files were created with the commercial version of PyMOL 3.0.5