Crash due to uncaught exception in DetectorSelectionDialog.py

[Finnjek]

orGUI may crash when changing the detector type in the 'Machine parameters' menu. The following error message is appearing:

Uncaught exception:
   File "C:\Users\supex679\AppData\Local\anaconda3\envs\orgui_git\Lib\site-packages\pyFAI\gui\dialog\DetectorSelectorDialog.py", line 679, in __modelChanged
    if isinstance(self.__detector, model):
       ~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^

TypeError: isinstance() arg 2 must be a type, a tuple of types, or a union

Judging from the output it seems like the error is caused by the pyFAI package (v. 2025.12.1) and not caused by orGUI. Therefore no action is necessary and we can probably only wait until the bug is fixed in pyFAI.
The error appears when one selects any detector manufacturer other than the active one. By first clicking Custom detector -> from file and only then selecting the intended detector manufacturer, the bug can be avoided. Besides that, I suggest to always select the detector in the config file.

[tifuchs]

I can reproduce the bug. Might be caused by orGUI, because we are not using the official API of pyFAI.

Have to investigate.

This bug should in any case not lead to a fatal crash.

[Finnjek]

I found out that the same error appears when using pyfai-calib2. The only difference is that the software doesn't crash.

(orgui_git) PS C:\Users\supex679\xray_tools\software> pyfai-calib2 ERROR:pyFAI-calib2.UNCAUGHT:isinstance() arg 2 must be a type, a tuple of types, or a union Traceback (most recent call last): File "C:\Users\supex679\AppData\Local\anaconda3\envs\orgui_git\Lib\site-packages\pyFAI\gui\dialog\DetectorSelectorDialog.py", line 679, in __modelChanged if isinstance(self.__detector, model): ~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^ TypeError: isinstance() arg 2 must be a type, a tuple of types, or a union

When downgrading to pyfai 2025.3.0 the error is gone. So I am certain that the error is on pyfai's side and we have to wait until it's fixed. We could add a try...except block, but the detector selection window will still crash each time the bug appears.

[tifuchs]

Did you report this to the pyFAI team?
They cannot fix it if they don't know this issue exists.

[Finnjek]

I just created an issue in the pyFAI repo: silx-kit/pyFAI#2818
The bug is still present using the latest pyFAI release 2026.2.1

[Finnjek]

The issue is fixed in the latest pyFAI release 2026.3.0.
We could exclude the pyFAI versions in which this error occurs (2025.12.0, 2025.12.1, 2026.2.0) in the requirements but in my opinion the bug is not so severe that this is necessary.

[tifuchs]

Will add a note upon next release to the changelog to communicate this issue.

Maybe we should exclude the versions.

Reopen issue as a reminder for the release.