This is the error that was logged when I tried to open (go to) and existing editor tab and it appeared blank.

ide.log

INFO [2017-08-24 11:44:57Z]: Launching iOS Simulator: /Library/Frameworks/Xamarin.iOS.framework/Versions/Current/bin/mlaunch -sdkroot "/Applications/Xcode.app/Contents/Developer" --launchsim "/Users/dave/Projects/BackBindings/iOS/bin/iPhoneSimulator/Debug/device-builds/iphone9.1-10.3.1/BackBindings.iOS.app" --argument=-monodevelop-port --argument=54439 --setenv=__XAMARIN_DEBUG_PORT__=54439 --sdk "10.3.1" --device=:v2:runtime=com.apple.CoreSimulator.SimRuntime.iOS-10-3,devicetype=com.apple.CoreSimulator.SimDeviceType.iPhone-7
ERROR [2017-08-24 11:45:02Z]: An unhandled exception has occured. Terminating Visual Studio? False
System.NullReferenceException: Object reference not set to an instance of an object
  at MonoDevelop.CSharp.PathedDocumentTextEditorExtension.<UpdateOwnerProjects>b__18_1 (MonoDevelop.Projects.DotNetProject p) [0x00000] in /Users/builder/data/lanes/4989/9c529966/source/monodevelop/main/src/addins/CSharpBinding/MonoDevelop.CSharp/PathedDocumentTextEditorExtension.cs:260 
  at System.Linq.Enumerable+WhereEnumerableIterator`1[TSource].MoveNext () [0x00037] in /private/tmp/source-mono-d15-3/bockbuild-d15-3/profiles/mono-mac-xamarin/build-root/mono-x64/external/corefx/src/System.Linq/src/System/Linq/Where.cs:149 
  at System.Collections.Generic.HashSet`1[T].UnionWith (System.Collections.Generic.IEnumerable`1[T] other) [0x00026] in /private/tmp/source-mono-d15-3/bockbuild-d15-3/profiles/mono-mac-xamarin/build-root/mono-x64/external/corefx/src/System.Collections/src/System/Collections/Generic/HashSet.cs:499 
  at System.Collections.Generic.HashSet`1[T]..ctor (System.Collections.Generic.IEnumerable`1[T] collection, System.Collections.Generic.IEqualityComparer`1[T] comparer) [0x0004b] in /private/tmp/source-mono-d15-3/bockbuild-d15-3/profiles/mono-mac-xamarin/build-root/mono-x64/external/corefx/src/System.Collections/src/System/Collections/Generic/HashSet.cs:140 
  at System.Collections.Generic.HashSet`1[T]..ctor (System.Collections.Generic.IEnumerable`1[T] collection) [0x00000] in /private/tmp/source-mono-d15-3/bockbuild-d15-3/profiles/mono-mac-xamarin/build-root/mono-x64/external/corefx/src/System.Collections/src/System/Collections/Generic/HashSet.cs:107 
  at MonoDevelop.CSharp.PathedDocumentTextEditorExtension+<>c__DisplayClass18_0.<UpdateOwnerProjects>b__0 () [0x00000] in /Users/builder/data/lanes/4989/9c529966/source/monodevelop/main/src/addins/CSharpBinding/MonoDevelop.CSharp/PathedDocumentTextEditorExtension.cs:260 
  at Mono.TextEditor.TextDocument+<>c.<InformRealizedComplete>b__316_0 (System.Action act) [0x00000] in /Users/builder/data/lanes/4989/9c529966/source/monodevelop/main/src/core/Mono.TextEditor.Shared/Mono.TextEditor/Document/TextDocument.cs:2079 
  at System.Collections.Generic.List`1[T].ForEach (System.Action`1[T] action) [0x00024] in /private/tmp/source-mono-d15-3/bockbuild-d15-3/profiles/mono-mac-xamarin/build-root/mono-x64/mcs/class/referencesource/mscorlib/system/collections/generic/list.cs:564 
  at Mono.TextEditor.TextDocument.InformRealizedComplete () [0x00010] in /Users/builder/data/lanes/4989/9c529966/source/monodevelop/main/src/core/Mono.TextEditor.Shared/Mono.TextEditor/Document/TextDocument.cs:2079 
  at MonoDevelop.SourceEditor.SourceEditorView.MonoDevelop.Ide.Editor.ITextEditorImpl.CreateNativeControl () [0x0000f] in /Users/builder/data/lanes/4989/9c529966/source/monodevelop/main/src/addins/MonoDevelop.SourceEditor2/MonoDevelop.SourceEditor/SourceEditorView.cs:2643 
  at MonoDevelop.Ide.Editor.TextEditor.CreateNativeWidget[T] () [0x00000] in /Users/builder/data/lanes/4989/9c529966/source/monodevelop/main/src/core/MonoDevelop.Ide/MonoDevelop.Ide.Editor/TextEditor.cs:989 
  at MonoDevelop.Components.Control.GetNativeWidget[T] () [0x0000d] in /Users/builder/data/lanes/4989/9c529966/source/monodevelop/main/src/core/MonoDevelop.Ide/MonoDevelop.Components/Control.cs:63 
  at MonoDevelop.Components.Control.op_Implicit (MonoDevelop.Components.Control d) [0x00000] in /Users/builder/data/lanes/4989/9c529966/source/monodevelop/main/src/core/MonoDevelop.Ide/MonoDevelop.Components/Control.cs:138 
  at MonoDevelop.Ide.Gui.SdiWorkspaceWindow.get_TabPage () [0x00008] in /Users/builder/data/lanes/4989/9c529966/source/monodevelop/main/src/core/MonoDevelop.Ide/MonoDevelop.Ide.Gui/SdiWorkspaceWindow.cs:135 
  at MonoDevelop.Ide.Gui.SdiWorkspaceWindow.OnRealized () [0x00016] in /Users/builder/data/lanes/4989/9c529966/source/monodevelop/main/src/core/MonoDevelop.Ide/MonoDevelop.Ide.Gui/SdiWorkspaceWindow.cs:151 
  at Gtk.Widget.realized_cb (System.IntPtr widget) [0x00010] in /private/tmp/source-mono-d15-3/bockbuild-d15-3/profiles/mono-mac-xamarin/build-root/gtk-sharp-None/gtk/generated/Widget.cs:658