Files: Crash when immediately switching while a folder is being loaded

[Jaiganeshkumaran]

Describe the bug
When you instantly switch while the folder loads, the app crashes.

To Reproduce
Steps to reproduce the behavior:

1. Create a new tab.
2. Click on a large folder pinned on the sidebar
3. Switch two the another tab very fast
4. App will crash

Expected behavior
App shouldn't crash and the refresh task should run in background.

Screenshots
If applicable, add screenshots to help explain your problem.

Desktop (please complete the following information):

• OS: Windows 10 Pro 2004
• App version: v0.13.0 (Downloaded from the Microsoft Store)

Additional context

2020-08-14 14:08:36.7060|ERROR|Files.App|Object reference not set to an instance of an object.|System.NullReferenceException: Object reference not set to an instance of an object.
   at Files.Filesystem.ItemViewModel.UpdateDirectoryInfo() + 0xf0
   at Files.Filesystem.ItemViewModel.<RapidAddItemsToCollectionAsync>d__70.MoveNext() + 0x970
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() + 0x21
   at System.Runtime.CompilerServices.AsyncMethodBuilderCore.<>c.<ThrowAsync>b__7_0(Object) + 0x1e
   at System.Action`1.Invoke(T) + 0x28
   at System.Threading.WinRTSynchronizationContext.Invoker.InvokeCore() + 0x33
   at System.Runtime.InteropServices.McgMarshal.ThrowOnExternalCallFailed(Int32, RuntimeTypeHandle) + 0x21
   at __Interop.ComCallHelpers.Call(__ComObject, RuntimeTypeHandle, Int32) + 0xb8
   at __Interop.ForwardComStubs.Stub_11[TThis](__ComObject, Int32) + 0x24
   at Microsoft.AppCenter.Utils.ApplicationLifecycleHelper.<.ctor>b__17_1(Object, UnhandledErrorDetectedEventArgs) + 0x3d
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() + 0x21
   at Microsoft.AppCenter.Utils.ApplicationLifecycleHelper.<.ctor>b__17_1(Object, UnhandledErrorDetectedEventArgs) + 0x75
   at System.EventHandler`1.Invoke(Object, TEventArgs) + 0x2e
   at __Interop.Intrinsics.HasThisCall__23[TArg0](Object, IntPtr, Object, TArg0) + 0x36
   at Files!<BaseAddress>+0x12a44a0

[issue-label-bot[bot]]

Issue-Label Bot is automatically applying the label bug to this issue, with a confidence of 0.99. Please mark this comment with :thumbsup: or :thumbsdown: to give our bot feedback!

Links: app homepage, dashboard and code for this bot.

[gave92]

@Jaiganeshkumaran could you check if this issue still exists on master? If we're lucky it got fixed with this

[Jaiganeshkumaran]

@gave92 But that's for the recycle bin. I will build the latest branch and try it.

[gave92]

@Jaiganeshkumaran yeah the PR was for the recyclebin, but from the stacktrace it looks like that change may solve this issue too (error is NullReferenceException and the PR adds a null check to the UpdateDirectoryInfo() function)

[Jaiganeshkumaran]

@gave92 I tried it and it still seems to crash but this time it needs to be done extremely fast (< 50ms). Regular users may not notice it but we should fix it.

[duke7553]

@Jaiganeshkumaran Hello there.

Was your stack trace the same as before after @gave92 PR?

[Jaiganeshkumaran]

@gave92 Yes the same stack trace after @gave92's PR. Nothing changed.

[duke7553]

@Jaiganeshkumaran We recently made improvements that could affect this area. Can you still reproduce this issue on the latest Store build?