Will my PCL code ever generate ` jobject must not be IntPtr.Zero`?

I've got a crash in my app that happens very rarely, and it happens when updating the value of a Label. Is there anything in my code that can generate a jobject must not be IntPtr.Zero or should I be looking at Xamarin.Forms for a solution?

at Android.Runtime.JNIEnv.CallVoidMethod (IntPtr jobject, IntPtr jmethod, Android.Runtime.JValue[] parms) [0x00000] in :0 at Android.Widget.TextView.set_TextFormatted (ICharSequence value) [0x00000] in :0 at Android.Widget.TextView.set_Text (System.String value) [0x00000] in :0 at Xamarin.Forms.Platform.Android.LabelRenderer.UpdateText () [0x00000] in :0 at Xamarin.Forms.Platform.Android.LabelRenderer.OnElementPropertyChanged (System.Object sender, System.ComponentModel.PropertyChangedEventArgs e) [0x00000] in :0 at TimeTracker.Droid.Renderers.ExtendedLabelRenderer.OnElementPropertyChanged (System.Object sender, System.ComponentModel.PropertyChangedEventArgs e) [0x00000] in :0 at (wrapper delegate-invoke) :invoke_void_object_PropertyChangedEventArgs (object,System.ComponentModel.PropertyChangedEventArgs) at (wrapper delegate-invoke) :invoke_void_object_PropertyChangedEventArgs (object,System.ComponentModel.PropertyChangedEventArgs) at Xamarin.Forms.BindableObject.OnPropertyChanged (System.String propertyName) [0x00000] in :0 at Xamarin.Forms.BindableObject.SetValueActual (Xamarin.Forms.BindableProperty property, Xamarin.Forms.BindablePropertyContext context, System.Object value, Boolean currentlyApplying, SetValueFlags attributes, Boolean silent) [0x00000] in :0 at Xamarin.Forms.BindableObject.SetValueCore (Xamarin.Forms.BindableProperty property, System.Object value, SetValueFlags attributes, SetValuePrivateFlags privateAttributes) [0x00000] in :0 at Xamarin.Forms.BindableObject.SetValueCore (Xamarin.Forms.BindableProperty property, System.Object value, SetValueFlags attributes) [0x00000] in :0 at Xamarin.Forms.BindingExpression.ApplyCore (System.Object sourceObject, Xamarin.Forms.BindableObject target, Xamarin.Forms.BindableProperty property, Boolean fromTarget) [0x00000] in :0 at Xamarin.Forms.BindingExpression.Apply (Boolean fromTarget) [0x00000] in :0 at Xamarin.Forms.BindingExpression+BindingExpressionPart.b__c () [0x00000] in :0 at Java.Lang.Thread+RunnableImplementor.Run () [0x00000] in :0 at Java.Lang.IRunnableInvoker.n_Run (IntPtr jnienv, IntPtr native__this) [0x00000] in :0 at (wrapper dynamic-method) object:1923d7ef-7884-4d84-9f53-cfe835bea9e3 (intptr,intptr)

I've attached a screenshot