Really weird ListBox bug

Targets macOS
1

I have a freeware app with crash reporting built in, and every once in a while I get a report of a NilObjectException with the following stack dump:

Sub Delegate.IM_Invoke( Listbox )
Sub AddHandler.Stub.15()
Sub Delegate.Invoke()
Sub Application._CallFunctionWithExceptionHandling()

this only happens on the Mac. I have not seen this being reported for the Windows or Linux builds of my app. Unfortunately, non of the users have provided any additional data, and the only reason why I’m even getting these reports is because it’s very easy just have the app send the report. I don’t know when exactly this happens, but from the rest of that data that is logged in the report, it appears that this may be happening very soon after the app was launched.
There are probably several hundred users using this app on a semi-frequent basis, and I get a report like this about every other weak. It doesn’t look like this is happening on a consistent level, and I have also never seen this happening on my Mac.

What is weird is that the stack dump doesn’t list any of my methods or event handlers I implemented. I also don’t use any delegates. I.e it doesn’t appear that any code I’ve written is doing anything at the time.

Has anyone seen anything like this before?

2

Can you duplicate this behavior in a small sample? I mean, can we see a sample working on windows and crashing in Mac?
If yes, you could open a case.

3

I can do that. However, the problem is, I have never personally seen this happen on my full app, and none of the users that reported this chose to include to include their e-mail address. I.e. I have no way of following up and have them try a small sample to confirm that it crashes also.

4

Probably I didn’t get it. Do you mean you can make it crash in your machine but fears that it will probably work on mine avoiding me to confirm the case?

5

I mean, that I can’t make it crash on either of my Macs. And given by the frequency I’m seeing this happen, I think this happens fairly rarely out in the user base. In any case, I’ll create an example to allow other to try and confirm the case. Is there a way to attach a Xojo project in these forums?

6

Use the feedback.app. Explain the case in details there. Explain the instability. Explain what kind the error appears when appears. Try to give details on how to reproduce. Attach the sample and pass the case number here.

7

Thanks. will do.