There I was, just devving along, when I hit F5 and this error pops up: C:\Program Files (x86)\MSBuild\Microsoft\WindowsXaml\v14.0\8.2\Microsoft.Windows.UI.Xaml.Common.targets(264,5): Xaml Internal Error error WMC9999: Object reference not set to an instance of an object. What does that even mean? Google shows me a variety of things that may cause this. But none of them helped me. …