Blender crash pop-up dialog appears when closing the program with this add-on enabled

[Sir-Coach]

Describe the bug
Reposted from this Blender bug report.
Blender LTS 4.5.3 crashes when closing the application with this add-on enabled, disabling auto-updates doesn't help.

System info
Blender version: Blender LTS 4.5.3, hash 67807e1800cc, date 09-09-2025 17:08
Add-on version: 1.2.0
Windows 10 Pro

Console log

C:\Blender Launcher\daily\blender-4.5.4-candidate+v45.57e187f8f5cd-windows.amd64-release>blender
Reloading external rigs...
Reloading external metarigs...
bl_ext.blender_org.Modifier_List_Fork: Registered 62 classes
register_class(...):
Warning: 'ShaderPanel' does not contain '_PT_' with prefix and suffix
register_class(...):
Warning: 'WorldPanel' does not contain '_PT_' with prefix and suffix
Read blend: "C:\Users\User\AppData\Local\Temp\blender\debug_logs\quit.blend"
Info: No new files have been packed
Info: Saved "quit.blend"
Saved session recovery to "C:\Users\User\AppData\Local\Temp\blender\debug_logs\quit.blend"
bl_ext.blender_org.Modifier_List_Fork: Unregistered 62 classes
Exception in thread Thread-2 (check_for_new_assets):
Traceback (most recent call last):
  File "C:\Blender Launcher\daily\blender-4.5.4-candidate+v45.57e187f8f5cd-windows.amd64-release\4.5\python\Lib\threading.py", line 1045, in _bootstrap_inner
    self.run()
  File "C:\Blender Launcher\daily\blender-4.5.4-candidate+v45.57e187f8f5cd-windows.amd64-release\4.5\python\Lib\threading.py", line 982, in run
    self._target(*self._args, **self._kwargs)
  File "C:\Users\User\AppData\Roaming\Blender Foundation\Blender\4.5\scripts\addons\polyhavenassets\utils\check_for_new_assets.py", line 21, in check_for_new_assets
    context.window_manager.pha_props.new_assets += 1
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AttributeError: 'WindowManager' object has no attribute 'pha_props'
Error   : EXCEPTION_ACCESS_VIOLATION
Address : 0x00007FFB49C27B95
Module  : python311.dll
Thread  : 000007d4
Writing: C:\Users\User\AppData\Local\Temp\blender\debug_logs\blender.crash.txt

To Reproduce

1. Download attached file from the Blender Bug Report linked above (unable to attach .blend files here)
2. Go to File > External Data > enable Automatically Pack Resources
3. Close Blender > Save
4. Crash dialog window appears

Can you reproduce the error starting from factory defaults?
No

[gregzaal]

Thanks for the report! This happens when the background thread to check for new assets - or other background threads such as active downloads - is still busy when Blender is quit. I'll be sure to include a fix in the next release.

The error is harmless and can be ignored.