NullReferenceException on Unity 2019.4.1

Description of the bug

NullReferenceException: Object reference not set to an instance of an object SimpleFileBrowser.RecycledListView.UpdateList () (at Assets/Plugins/SimpleFileBrowser/Scripts/SimpleRecycledListView/RecycledListView.cs:55) SimpleFileBrowser.FileBrowser.RefreshFiles (System.Boolean pathChanged) (at Assets/Plugins/SimpleFileBrowser/Scripts/FileBrowser.cs:1420) SimpleFileBrowser.FileBrowser.OnShowHiddenFilesToggleChanged () (at Assets/Plugins/SimpleFileBrowser/Scripts/FileBrowser.cs:1071) UnityEngine.Events.InvokableCall.Invoke () (at <4eca0aa85b9643a199169bb7e91fc8d3>:0) UnityEngine.Events.UnityEvent`1[T0].Invoke (T0 arg0) (at <4eca0aa85b9643a199169bb7e91fc8d3>:0) UnityEngine.UI.Toggle.Rebuild (UnityEngine.UI.CanvasUpdate executing) (at D:/unity/2019.4.0f1/Editor/Data/Resources/PackageManager/BuiltInPackages/com.unity.ugui/Runtime/UI/Core/Toggle.cs:130) UnityEngine.UI.CanvasUpdateRegistry.PerformUpdate () (at D:/unity/2019.4.0f1/Editor/Data/Resources/PackageManager/BuiltInPackages/com.unity.ugui/Runtime/UI/Core/CanvasUpdateRegistry.cs:177) UnityEngine.UI.ScrollRect:LateUpdate() (at D:/unity/2019.4.0f1/Editor/Data/Resources/PackageManager/BuiltInPackages/com.unity.ugui/Runtime/UI/Core/ScrollRect.cs:805)

Reproduction steps

FileBrowser.ShowLoadDialog((paths => {
                //todo
}), () => {
                //todo
});

Platform specs

Please provide the following info if this is a Unity 3D repository.

• Unity version: 2019.4.1
• Platform: Windows
• How did you download the plugin: Asset Store version 1.3.6

Additional info

Please check Logcat (Android) or Xcode console (iOS) for any meaningful error messages and include them here.

[artur-ag]

Not during the start of the scene, no, it gets created when I invoke the file browser by clicking on a UI button in my own Canvas. ~But when I was getting the error yesterday, I can’t remember if the SimpleFileBrowserCanvas object was there from the beginning or not, and now I can’t reproduce the exception.~

I did two changes in the SimpleFileBrowserCanvas: I disabled the EventSystem, because I already have one in my scene, and changed the CanvasScaler reference resolution.

EDIT: I managed to reproduce the bug!! It happened while I started the game in the editor while having the SimpleFileBrowserCanvas prefab opened in Prefab mode. Here are the steps to reproduce it in Unity 2020.2.1f1:

1. Create an empty scene (I tried with my existing scene and with an empty one, and it happened both times).
2. Double-click SimpleFileBrowserCanvas.prefab in the Project panel. This will open it in Prefab mode, and makes the scene panel background blue.
3. With the prefab still open, press Play.
4. The following exception occurs right after starting:

NullReferenceException: Object reference not set to an instance of an object
SimpleFileBrowser.RecycledListView.UpdateList () (at Assets/Plugins/SimpleFileBrowser/Scripts/SimpleRecycledListView/RecycledListView.cs:55)
SimpleFileBrowser.FileBrowser.RefreshFiles (System.Boolean pathChanged) (at Assets/Plugins/SimpleFileBrowser/Scripts/FileBrowser.cs:1621)
SimpleFileBrowser.FileBrowser.OnShowHiddenFilesToggleChanged () (at Assets/Plugins/SimpleFileBrowser/Scripts/FileBrowser.cs:1266)
UnityEngine.Events.InvokableCall.Invoke () (at <e414e10bfe5f45729ff122f3359de21b>:0)
UnityEngine.Events.UnityEvent`1[T0].Invoke (T0 arg0) (at <e414e10bfe5f45729ff122f3359de21b>:0)
UnityEngine.UI.Toggle.Rebuild (UnityEngine.UI.CanvasUpdate executing) (at C:/Program Files/Unity/Hub/Editor/2020.2.1f1/Editor/Data/Resources/PackageManager/BuiltInPackages/com.unity.ugui/Runtime/UI/Core/Toggle.cs:130)
UnityEngine.UI.CanvasUpdateRegistry.PerformUpdate () (at C:/Program Files/Unity/Hub/Editor/2020.2.1f1/Editor/Data/Resources/PackageManager/BuiltInPackages/com.unity.ugui/Runtime/UI/Core/CanvasUpdateRegistry.cs:182)
UnityEngine.UI.ScrollRect:LateUpdate() (at C:/Program Files/Unity/Hub/Editor/2020.2.1f1/Editor/Data/Resources/PackageManager/BuiltInPackages/com.unity.ugui/Runtime/UI/Core/ScrollRect.cs:808)

I must’ve had the prefab mode open yesterday and didn’t realize it.

[yasirkula]

Awesome! I was able to reproduce the error on 2018.4, too.