Fix by workaround crash on LabelRenderer and when changing themes #1689 (#1690)

src/App/Utilities/ThemeManager.cs

@@ -4,6 +4,9 @@ using Bit.App.Services;
 using Bit.App.Styles;
 using Bit.Core;
 using Xamarin.Forms;
+#if !FDROID
+using Microsoft.AppCenter.Crashes;
+#endif
 
 namespace Bit.App.Utilities
 {
@@ -13,6 +16,8 @@ namespace Bit.App.Utilities
         public static Func<ResourceDictionary> Resources = () => null;
 
         public static void SetThemeStyle(string name, ResourceDictionary resources)
+        {
+            try
             {
                 Resources = () => resources;
 
@@ -71,6 +76,22 @@ namespace Bit.App.Utilities
                     resources.MergedDictionaries.Add(new iOS());
                 }
             }
+            catch (InvalidOperationException ioex) when (ioex.Message != null && ioex.Message.StartsWith("Collection was modified"))
+            {
+                // https://github.com/bitwarden/mobile/issues/1689 There are certain scenarios where this might cause "collection was modified; enumeration operation may not execute"
+                // the way I found to prevent this for now was to catch the exception here and move on.
+                // Because on the screens that I found it to happen, the screen is being closed while trying to apply the resources
+                // so we shouldn't be introducing any issues.
+                // TODO: Maybe something like this https://github.com/matteobortolazzo/HtmlLabelPlugin/pull/113 can be implemented to avoid this
+                // on html labels.
+            }
+            catch (Exception ex)
+            {
+#if !FDROID
+                Crashes.TrackError(ex);
+#endif
+            }
+        }
 
         public static void SetTheme(bool android, ResourceDictionary resources)
         {

src/iOS.Core/Renderers/CustomLabelRenderer.cs

@@ -1,4 +1,5 @@
-using System.ComponentModel;
+using System;
+using System.ComponentModel;
 using Bit.iOS.Core.Renderers;
 using Bit.iOS.Core.Utilities;
 using UIKit;
@@ -20,8 +21,20 @@ namespace Bit.iOS.Core.Renderers
 		}
 
 		protected override void OnElementPropertyChanged(object sender, PropertyChangedEventArgs e)
+		{
+            try
             {
 				base.OnElementPropertyChanged(sender, e);
+			}
+			catch (NullReferenceException)
+			{
+				// Do nothing...
+				// There is an issue on Xamarin Forms which throws a null reference
+				// https://appcenter.ms/users/kspearrin/apps/bitwarden/crashes/errors/534094859u/overview
+				// TODO: Maybe something like this https://github.com/matteobortolazzo/HtmlLabelPlugin/pull/113 can be implemented to avoid this
+				// on html labels.
+			}
+
 			if (e.PropertyName == Label.FontProperty.PropertyName ||
 				e.PropertyName == Label.TextProperty.PropertyName ||
 				e.PropertyName == Label.FormattedTextProperty.PropertyName)
@@ -32,6 +45,9 @@ namespace Bit.iOS.Core.Renderers
 
 		private void UpdateFont()
 		{
+			if (Element is null || Control is null)
+				return;
+
 			var pointSize = iOSHelpers.GetAccessibleFont<Label>(Element.FontSize);
 			if (pointSize != null)
 			{