Project Tiny scene becoming regular scene

This has happened to me twice. I am working on a Project Tiny scene when suddenly the scene seems to turn into a regular Unity scene. I no longer have the options to create or load entity groups in the hierarchy, everything appears as it would were I to create a regular Unity scene, and when I choose to create any Project Tiny assets in my scene I get the following error:

NullReferenceException: Object reference not set to an instance of an object
Unity.Tiny.EntityTemplateMenuItems.CreateAsRoot (System.String name, Unity.Tiny.EntityTemplate template) (at Library/PackageCache/com.unity.tiny@0.13.4-preview/Editor/EntityTemplates/EntityTemplateMenuItems.cs:72)
Unity.Tiny.EntityTemplateMenuItems+<CreateWithContext>d__21.MoveNext () (at Library/PackageCache/com.unity.tiny@0.13.4-preview/Editor/EntityTemplates/EntityTemplateMenuItems.cs:39)
System.Collections.Generic.List`1[T]..ctor (System.Collections.Generic.IEnumerable`1[T] collection) (at <ac823e2bb42b41bda67924a45a0173c3>:0)
System.Linq.Enumerable.ToList[TSource] (System.Collections.Generic.IEnumerable`1[T] source) (at <1b13ba6391c74847bbc3eddc86df7eee>:0)
Unity.Tiny.EntityTemplateMenuItems.CreateWithContext (System.String name, Unity.Tiny.EntityTemplate template, System.Boolean alwaysAsRoot, Unity.Tiny.IRegistryObject[] context) (at Library/PackageCache/com.unity.tiny@0.13.4-preview/Editor/EntityTemplates/EntityTemplateMenuItems.cs:30)
Unity.Tiny.EntityTemplateMenuItems.Sprite (Unity.Tiny.IRegistryObject[] context) (at Library/PackageCache/com.unity.tiny@0.13.4-preview/Editor/EntityTemplates/EntityTemplateMenuItems.cs:115)
Unity.Tiny.MenuItem_Sprite.Sprite () (at Library/PackageCache/com.unity.tiny@0.13.4-preview/Editor/Generated/MenuItems/MenuItem_Sprite.cs:17)
UnityEditor.GenericMenu:CatchMenu(Object, String[], Int32)
​

I have tried reinstalling the Project Tiny package, but this didn't fix the problem. All other sample Project Tiny scenes open with no issues in the same project. This has happened rather abruptly both times, so I can't say for sure what exactly I was doing to trigger the problem, but I am fairly sure this has happened when I exit play mode.

Any ways to fix this or tips to avoid it in the future would be appreciated.

 

I've just noticed that when you enter play mode in a Project Tiny scene Unity appears to launch a normal Unity scene called "ProjectTiny - DO NOT EDIT" for a moment before entering it's final phase of play mode a couple of seconds later (Don't know what to call this mode. The hierarchy is empty and the QR code, active client, etc. are displayed in the game window.)
Is it possible that the Project Tiny scene can be "corrupted" in some way if you exit play mode while the "ProjectTiny - DO NOT EDIT" scene is active?