System.ArgumentNullException when testing on Motorola Nexus 6

I am having a very weird issue with my Xamarin.Forms 1.5.0 app. I have been testing and debugging it in the Android emulator on my Windows 10 PC without any problems. When I connected my Motorola Nexus 6 and deploying my app to it, I suddenly started getting the following exception:

10-24 20:05:51.109 I/MonoDroid(31398): UNHANDLED EXCEPTION:
10-24 20:05:51.113 I/MonoDroid(31398): System.ArgumentNullException: Argument cannot be null.
10-24 20:05:51.113 I/MonoDroid(31398): Parameter name: source
10-24 20:05:51.113 I/MonoDroid(31398): at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw () [0x0000b] in /Users/builder/data/lanes/2185/53fce373/source/mono/mcs/class/corlib/System.Runtime.ExceptionServices/ExceptionDispatchInfo.cs:61
10-24 20:05:51.113 I/MonoDroid(31398): at System.Runtime.CompilerServices.AsyncMethodBuilderCore.<ThrowAsync>m__0 (object) [0x00000] in /Users/builder/data/lanes/2185/53fce373/source/mono/external/referencesource/mscorlib/system/runtime/compilerservices/AsyncMethodBuilder.cs:1006
10-24 20:05:51.113 I/MonoDroid(31398): at Android.App.SyncContext/<Post>c__AnonStorey0.<>m__0 () [0x00000] in /Users/builder/data/lanes/2185/53fce373/source/monodroid/src/Mono.Android/src/Android.App/SyncContext.cs:18
10-24 20:05:51.113 I/MonoDroid(31398): at Java.Lang.Thread/RunnableImplementor.Run () [0x0000b] in /Users/builder/data/lanes/2185/53fce373/source/monodroid/src/Mono.Android/src/Java.Lang/Thread.cs:36
10-24 20:05:51.113 I/MonoDroid(31398): at Java.Lang.IRunnableInvoker.n_Run (intptr,intptr) [0x00009] in /Users/builder/data/lanes/2185/53fce373/source/monodroid/src/Mono.Android/platforms/android-22/src/generated/Java.Lang.IRunnable.cs:71
10-24 20:05:51.113 I/MonoDroid(31398): at (wrapper dynamic-method) object.b749f634-13ea-4782-9a8a-1ed296ff8bb1 (intptr,intptr) <IL 0x00011, 0x00043>

The full output from the debugger can be found here: http://pastebin.com/uhW4Si1J

I have been trying to identify the bug but I haven't had any luck so far. Everything works fine in my emulator but it crashes on my phone.

Can anybody help me out?