When I touch webview content and then somewhere outside after the app crashes

Question

I'm pretty new to this and also this isn't my code. I find it hard to figure anything out, but I'm doing my best. So the case is, that I have Grid element which contains FlipView and another Grid (it contains 4 SelectorButtons). Inside FlipView I have 3 WebViews and Frame. And now something I'm not able to figure out - when I interact with webview somehow (scroll for an instance) and tap any of buttons the app crashes. It throws System.ArgumentException: Value does not fall within the expected range. Touching Frame and then buttons works fine. Here's xaml code and buttons commands. Xaml:

        <FlipView.ItemsPanel>
            <ItemsPanelTemplate>
                <VirtualizingStackPanel Orientation="Horizontal" />
            </ItemsPanelTemplate>
        </FlipView.ItemsPanel>



        <WebView x:Name="web1"
                 Source="{Binding Model.Widget1Url}"
                 Height="Auto"
                 Width="Auto"
                 HorizontalAlignment="Stretch"
                 VerticalAlignment="Stretch"
                 ScrollViewer.ZoomMode="Disabled"
                 ScrollViewer.VerticalScrollBarVisibility="Disabled"                    

                 Visibility="Visible" ManipulationMode="None" IsTapEnabled="False"/>

        <WebView x:Name="web2"
                 Source="{Binding Model.Widget2Url}"
                 Height="Auto"
                 Width="Auto"
                 HorizontalAlignment="Stretch"
                 VerticalAlignment="Stretch"
                 ScrollViewer.ZoomMode="Disabled"
                 ScrollViewer.VerticalScrollBarVisibility="Disabled"                    

                 Visibility="Visible" ManipulationMode="None"/>

        <WebView x:Name="web3"
                 Source="{Binding Model.Widget3Url}"
                 Height="Auto"
                 Width="Auto"
                 HorizontalAlignment="Stretch"
                 VerticalAlignment="Stretch"
                 ScrollViewer.ZoomMode="Disabled"
                 ScrollViewer.VerticalScrollBarVisibility="Disabled"                    
                 Visibility="Visible" ManipulationMode="None"/>

        <Frame Height="Auto"
               Width="Auto"
               HorizontalAlignment="Stretch"
                ManipulationMode="All" ManipulationCompleted="FlipView_ManipulationCompleted"  ManipulationStarted="FlipViewItem_ManipulationDelta"
               VerticalAlignment="Stretch"   
               Background="White"
               x:Name="contentFrame" DataContext="{Binding Model.UserLoginViewModel}"/>


    </FlipView>

    <Grid Grid.Row="1" VerticalAlignment="Bottom">
        <Grid.RowDefinitions>
            <RowDefinition Height="60"></RowDefinition>
        </Grid.RowDefinitions>
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="*"/>
            <ColumnDefinition Width="*"/>
            <ColumnDefinition Width="*"/>
            <ColumnDefinition Width="*"/>
        </Grid.ColumnDefinitions>

        <controls:SelectorButton x:Name="B1" Grid.Row="0" Grid.Column="0" Source="../images/tab_01.png" ActiveSource="../images/tab_active_01.png" ButtonCommand="{Binding Model.SetWebView1Command}"/>
        <controls:SelectorButton x:Name="B2" Grid.Row="0" Grid.Column="1" Source="../images/tab_02.png" ActiveSource="../images/tab_active_02.png" ButtonCommand="{Binding Model.SetWebView2Command}"/>
        <controls:SelectorButton x:Name="B3" Grid.Row="0" Grid.Column="2" Source="../images/tab_03.png" ActiveSource="../images/tab_active_03.png" ButtonCommand="{Binding Model.SetWebView3Command}"/>
        <controls:SelectorButton x:Name="B4" Grid.Row="0" Grid.Column="3" Source="../images/tab_04.png" ActiveSource="../images/tab_active_04.png" ButtonCommand="{Binding Model.LoginCommand}" />
    </Grid>
</Grid>

Commands:

private async void SetWebView1()
    {
        if (FlipView.SelectedIndex == 3)
        {
            FlipView.SelectedIndex = 2;
            await Task.Delay(TimeSpan.FromSeconds(0.1));

            FlipView.SelectedIndex = 1;
            await Task.Delay(TimeSpan.FromSeconds(0.1));
        }

        if (FlipView.SelectedIndex == 2)
        {
            FlipView.SelectedIndex = 1;
            await Task.Delay(TimeSpan.FromSeconds(0.1));
        }

        FlipView.SelectedIndex = 0;
    }

    private async void SetWebView2()
    {
        if (FlipView.SelectedIndex == 3)
        {
            FlipView.SelectedIndex = 2;
            await Task.Delay(TimeSpan.FromSeconds(0.1));
        }
        FlipView.SelectedIndex = 1;

    }

    private async void SetWebView3()
    {
        if (FlipView.SelectedIndex == 0)
        {
            FlipView.SelectedIndex = 1;
            await Task.Delay(TimeSpan.FromSeconds(0.1));
        }
        FlipView.SelectedIndex = 2;
    }

    public async void SetLogin()
    {
        if (FlipView.SelectedIndex == 0)
        {
            FlipView.SelectedIndex = 1;
            await Task.Delay(TimeSpan.FromSeconds(0.1));

            FlipView.SelectedIndex = 2;
            await Task.Delay(TimeSpan.FromSeconds(0.1));
        }

        if (FlipView.SelectedIndex == 1)
        {
            FlipView.SelectedIndex = 2;
            await Task.Delay(TimeSpan.FromSeconds(0.1));
        }

        FlipView.SelectedIndex = 3;
    }

As I mentioned before, that code was written by someone else and I don't know why something is that way and something other way. Any suggestion would be much appreciated.

Answer 1

I was able to manage app not to crash. Line which was causing problems was for example FlipView.SelectedIndex = 1; What I did was to put this statement into try-catch block. It doesn't crash anymore and, what is interesting, executes this line so app works like it's intended.