Xamarin.Forms.iOS app crashes in Main.cs Value cannot be null. Parameter name: other

Hi,

I have an app which is used for shopping.

When users clear the shopping cart (which is linked to an ObservableCollection), the colour of the label changes in the ViewModel.

It works perfectly fine, but on iOS, it crashes with a strange exception. How can I track which line of code or which element exactly is causing that issue?

  at Foundation.NSMutableAttributedString..ctor (Foundation.NSAttributedString other) [0x0000e] in /Library/Frameworks/Xamarin.iOS.framework/Versions/12.2.1.13/src/Xamarin.iOS/Foundation/NSMutableAttributedString.g.cs:134 
  at Xamarin.Forms.Platform.iOS.LabelRenderer.UpdateTextDecorations () [0x0001e] in D:\a\1\s\Xamarin.Forms.Platform.iOS\Renderers\LabelRenderer.cs:221 
  at Xamarin.Forms.Platform.iOS.LabelRenderer.OnElementPropertyChanged (System.Object sender, System.ComponentModel.PropertyChangedEventArgs e) [0x0009d] in D:\a\1\s\Xamarin.Forms.Platform.iOS\Renderers\LabelRenderer.cs:192 
  at (wrapper delegate-invoke) <Module>.invoke_void_object_PropertyChangedEventArgs(object,System.ComponentModel.PropertyChangedEventArgs)
  at Xamarin.Forms.BindableObject.OnPropertyChanged (System.String propertyName) [0x00000] in D:\a\1\s\Xamarin.Forms.Core\BindableObject.cs:173 
  at Xamarin.Forms.Element.OnPropertyChanged (System.String propertyName) [0x00000] in D:\a\1\s\Xamarin.Forms.Core\Element.cs:338 
  at Xamarin.Forms.BindableObject.SetValueActual (Xamarin.Forms.BindableProperty property, Xamarin.Forms.BindableObject+BindablePropertyContext context, System.Object value, System.Boolean currentlyApplying, Xamarin.Forms.Internals.SetValueFlags attributes, System.Boolean silent) [0x00114] in D:\a\1\s\Xamarin.Forms.Core\BindableObject.cs:622 
  at Xamarin.Forms.BindableObject.SetValueCore (Xamarin.Forms.BindableProperty property, System.Object value, Xamarin.Forms.Internals.SetValueFlags attributes, Xamarin.Forms.BindableObject+SetValuePrivateFlags privateAttributes) [0x0015b] in D:\a\1\s\Xamarin.Forms.Core\BindableObject.cs:422 
  at Xamarin.Forms.BindingExpression.ApplyCore (System.Object sourceObject, Xamarin.Forms.BindableObject target, Xamarin.Forms.BindableProperty property, System.Boolean fromTarget) [0x00220] in D:\a\1\s\Xamarin.Forms.Core\BindingExpression.cs:167 
  at Xamarin.Forms.BindingExpression.Apply (System.Object sourceObject, Xamarin.Forms.BindableObject target, Xamarin.Forms.BindableProperty property) [0x0006b] in D:\a\1\s\Xamarin.Forms.Core\BindingExpression.cs:78 
  at Xamarin.Forms.Binding.Apply (System.Object context, Xamarin.Forms.BindableObject bindObj, Xamarin.Forms.BindableProperty targetProperty, System.Boolean fromBindingContextChanged) [0x00057] in D:\a\1\s\Xamarin.Forms.Core\Binding.cs:131 
  at Xamarin.Forms.BindableObject.ApplyBindings (System.Boolean skipBindingContext, System.Boolean fromBindingContextChanged) [0x00041] in D:\a\1\s\Xamarin.Forms.Core\BindableObject.cs:453 
  at Xamarin.Forms.BindableObject.SetInheritedBindingContext (Xamarin.Forms.BindableObject bindable, System.Object value) [0x0005a] in D:\a\1\s\Xamarin.Forms.Core\BindableObject.cs:158 
  at Xamarin.Forms.Element.SetChildInheritedBindingContext (Xamarin.Forms.Element child, System.Object context) [0x00000] in D:\a\1\s\Xamarin.Forms.Core\Element.cs:485 
  at Xamarin.Forms.Element.<OnBindingContextChanged>b__74_0 (Xamarin.Forms.BindableObject child, System.Object bc) [0x00000] in D:\a\1\s\Xamarin.Forms.Core\Element.cs:293 
  at Xamarin.Forms.BindableObjectExtensions.PropagateBindingContext[T] (Xamarin.Forms.BindableObject self, System.Collections.Generic.IList`1[T] children, System.Action`2[T1,T2] setChildBindingContext) [0x0002c] in D:\a\1\s\Xamarin.Forms.Core\BindableObjectExtensions.cs:28 
  at Xamarin.Forms.Element.OnBindingContextChanged () [0x00000] in D:\a\1\s\Xamarin.Forms.Core\Element.cs:291 
  at Xamarin.Forms.View.OnBindingContextChanged () [0x0000c] in D:\a\1\s\Xamarin.Forms.Core\View.cs:158 
  at Xamarin.Forms.Grid.OnBindingContextChanged () [0x00006] in D:\a\1\s\Xamarin.Forms.Core\Grid.cs:147 
  at Xamarin.Forms.BindableObject.SetInheritedBindingContext (Xamarin.Forms.BindableObject bindable, System.Object value) [0x00062] in D:\a\1\s\Xamarin.Forms.Core\BindableObject.cs:159 
  at Xamarin.Forms.Element.SetChildInheritedBindingContext (Xamarin.Forms.Element child, System.Object context) [0x00000] in D:\a\1\s\Xamarin.Forms.Core\Element.cs:485 
  at Xamarin.Forms.Element.<OnBindingContextChanged>b__74_0 (Xamarin.Forms.BindableObject child, System.Object bc) [0x00000] in D:\a\1\s\Xamarin.Forms.Core\Element.cs:293 
  at Xamarin.Forms.BindableObjectExtensions.PropagateBindingContext[T] (Xamarin.Forms.BindableObject self, System.Collections.Generic.IList`1[T] children, System.Action`2[T1,T2] setChildBindingContext) [0x0002c] in D:\a\1\s\Xamarin.Forms.Core\BindableObjectExtensions.cs:28 
  at Xamarin.Forms.Element.OnBindingContextChanged () [0x00000] in D:\a\1\s\Xamarin.Forms.Core\Element.cs:291 
  at Xamarin.Forms.View.OnBindingContextChanged () [0x0000c] in D:\a\1\s\Xamarin.Forms.Core\View.cs:158 
  at Xamarin.Forms.BindableObject.SetInheritedBindingContext (Xamarin.Forms.BindableObject bindable, System.Object value) [0x00062] in D:\a\1\s\Xamarin.Forms.Core\BindableObject.cs:159 
  at Xamarin.Forms.Element.SetChildInheritedBindingContext (Xamarin.Forms.Element child, System.Object context) [0x00000] in D:\a\1\s\Xamarin.Forms.Core\Element.cs:485 
  at Xamarin.Forms.Element.<OnBindingContextChanged>b__74_0 (Xamarin.Forms.BindableObject child, System.Object bc) [0x00000] in D:\a\1\s\Xamarin.Forms.Core\Element.cs:293 
  at Xamarin.Forms.BindableObjectExtensions.PropagateBindingContext[T] (Xamarin.Forms.BindableObject self, System.Collections.Generic.IList`1[T] children, System.Action`2[T1,T2] setChildBindingContext) [0x0002c] in D:\a\1\s\Xamarin.Forms.Core\BindableObjectExtensions.cs:28 
  at Xamarin.Forms.Element.OnBindingContextChanged () [0x00000] in D:\a\1\s\Xamarin.Forms.Core\Element.cs:291 
  at Xamarin.Forms.Cell.OnBindingContextChanged () [0x00000] in D:\a\1\s\Xamarin.Forms.Core\Cells\Cell.cs:144 
  at Xamarin.Forms.BindableObject.BindingContextPropertyChanged (Xamarin.Forms.BindableObject bindable, System.Object oldvalue, System.Object newvalue) [0x0000f] in D:\a\1\s\Xamarin.Forms.Core\BindableObject.cs:473 
  at Xamarin.Forms.BindableObject.SetValueActual (Xamarin.Forms.BindableProperty property, Xamarin.Forms.BindableObject+BindablePropertyContext context, System.Object value, System.Boolean currentlyApplying, Xamarin.Forms.Internals.SetValueFlags attributes, System.Boolean silent) [0x00120] in D:\a\1\s\Xamarin.Forms.Core\BindableObject.cs:624 
  at Xamarin.Forms.BindableObject.SetValueCore (Xamarin.Forms.BindableProperty property, System.Object value, Xamarin.Forms.Internals.SetValueFlags attributes, Xamarin.Forms.BindableObject+SetValuePrivateFlags privateAttributes) [0x0015b] in D:\a\1\s\Xamarin.Forms.Core\BindableObject.cs:422 
  at Xamarin.Forms.BindableObject.SetValue (Xamarin.Forms.BindableProperty property, System.Object value, System.Boolean fromStyle, System.Boolean checkAccess) [0x0003d] in D:\a\1\s\Xamarin.Forms.Core\BindableObject.cs:572 
  at Xamarin.Forms.BindableObject.SetValue (Xamarin.Forms.BindableProperty property, System.Object value) [0x00000] in D:\a\1\s\Xamarin.Forms.Core\BindableObject.cs:122 
  at Xamarin.Forms.BindableObject.set_BindingContext (System.Object value) [0x00000] in D:\a\1\s\Xamarin.Forms.Core\BindableObject.cs:26 
  at Xamarin.Forms.Internals.TemplatedItemsList`2+<UnhookItem>d__154[TView,TItem].MoveNext () [0x000a5] in D:\a\1\s\Xamarin.Forms.Core\TemplatedItemsList.cs:1207 
--- End of stack trace from previous location where exception was thrown ---
  at System.Runtime.CompilerServices.AsyncMethodBuilderCore+<>c.<ThrowAsync>b__6_0 (System.Object state) [0x00000] in /Library/Frameworks/Xamarin.iOS.framework/Versions/12.2.1.13/src/Xamarin.iOS/mcs/class/referencesource/mscorlib/system/runtime/compilerservices/AsyncMethodBuilder.cs:1023 
  at Foundation.NSAsyncSynchronizationContextDispatcher.Apply () [0x00000] in /Library/Frameworks/Xamarin.iOS.framework/Versions/12.2.1.13/src/Xamarin.iOS/Foundation/NSAction.cs:178 
--- End of stack trace from previous location where exception was thrown ---
  at (wrapper managed-to-native) UIKit.UIApplication.UIApplicationMain(int,string[],intptr,intptr)
  at UIKit.UIApplication.Main (System.String[] args, System.IntPtr principal, System.IntPtr delegate) [0x00005] in /Library/Frameworks/Xamarin.iOS.framework/Versions/12.2.1.13/src/Xamarin.iOS/UIKit/UIApplication.cs:79 
  at UIKit.UIApplication.Main (System.String[] args, System.String principalClassName, System.String delegateClassName) [0x0002c] in /Library/Frameworks/Xamarin.iOS.framework/Versions/12.2.1.13/src/Xamarin.iOS/UIKit/UIApplication.cs:63 
  at VanXApp.iOS.Application.Main (System.String[] args) [0x00002] in C:\Users\VanX\source\repos\VanXApp\VanXApp\VanXApp.iOS\Main.cs:19