dpropertysheet.lua attempt to call method GetPanel

Hi

Sometimes my users are getting the following lua error:



[ERROR] lua/vgui/dpropertysheet.lua:220: attempt to call method 'GetPanel' (a nil value)
  1. Func - lua/vgui/dpropertysheet.lua:220
   2. Run - lua/derma/derma_animation.lua:23
    3. unknown - lua/vgui/dpropertysheet.lua:214


I’m having a hard time diagnosing it as the stacktrace does not point me to anywhere in my own files rather than the built-in garrysmod files. Is there any trick to this that I use? I cannot reproduce the error myself and there does not seem to be a specific sequence of events that leads up to it happening.

Thanks

Is there an addon you installed recently that could have caused this?

The server only runs falcos prop protection and prometheus, both of which have been present for half a year

I think some addon or something is using DPropertySheet non standardly on your server. Either that addon uses DPropertySheet.SetActiveTab function improperly, or they do not use DTabs for tabs, as in, they do not use DPropertySheet.AddSheet()

[editline]2nd January 2017[/editline]

Or they set m_pActiveTab manually, which they shouldn’t do.

The interesting thing is that it’s only happening to about 25% of our players