HockeyClient.Flush null ref about hockeysdk-windows

[quincycs]

@mtaron not a great solution, but I typically put a Task.Delay of 2 or more seconds then flush. I have this issue as well, but for a different scenario.

[schuettecarsten]

@mtaron Why is it useful to call Flush in EnteredBackground?

[mtaron]

@schuettecarsten These docs say the following:

Normally the SDK sends data at times chosen to minimize impact on the user. However, in some cases you might want to flush the buffer - for example, if you are using the SDK in an application that shuts down.

As I understand it, EnteredBackground is the write place to put "pre-shutdown" work in a UWP app. Plus, I aggregate a bunch of rendering performance metrics locally using RunningStatistics and I need to choose some place to stop aggregating and report them. It could be elsewhere, but this seemed like a convenient place.

[schuettecarsten]

I think that EnteredBackground is also triggered when the application is sent to background but continues to run in the background. If you need to catch the "pre-shutdown" moment, I would use CoreWindow.Closed event which is also documented as "fired when the App terminates" or the Suspend event of the App (which is also fired when the App is closed).

[mtaron]

Hm, perhaps. What do you think about the "Save your state" section here? Seems like it could apply to flushing telemetry as well.

[schuettecarsten]

Ahh, okay, something was added/changed in 1607. Our app has to be compatible to 10240 for next two years, so we cannot use the new APIs.

[achocron]

This issue has been resolved with the latest NuGet package releases. Upgrading to 4.1.6 should solve the problem.

[quincycs]

@achocron thx. It fixes the null ref by the look of the code change but now there is a possible side affect that flush might not flush

[izikl]

@quincycs yep. We are postponing the app initialization by 1 sec to avoid performance hit on app startup.

We can, however, revise and improve this design. I have opened issue #109 to track it.

[quincycs]

Thx. I'll comment on that