ShapesRenderEditor throwing exceptions when playing in editor

I don't recall seeing this before, so not sure what caused it, but in the editor every time I hit Play to test out my game, I see a series of four errors in the console that seem to tie into the ShapesRenderEditor trying to create a SerilizedObject.  I'm not sure why editor code is even running at this point, but that is what I'm seeing:

NullReferenceException: Object reference not set to an instance of an object
UnityEditor.GameObjectInspector.OnDisable () (at <94e1644530894ca4afcc0afbfd6605d3>:0)

SerializedObjectNotCreatableException: Object at index 0 is null
UnityEditor.Editor.CreateSerializedObject () (at <94e1644530894ca4afcc0afbfd6605d3>:0)
UnityEditor.Editor.GetSerializedObjectInternal () (at <94e1644530894ca4afcc0afbfd6605d3>:0)
UnityEditor.Editor.get_serializedObject () (at <94e1644530894ca4afcc0afbfd6605d3>:0)
UnityEditor.TransformInspector.OnEnable () (at <94e1644530894ca4afcc0afbfd6605d3>:0)

InvalidCastException: Specified cast is not valid.
Shapes.ShapeRendererEditor+<>c.<onenable>b__36_0 (UnityEngine.Object t) (at Assets/Shapes/Scripts/Editor/Components/ShapeRendererEditor.cs:108)
System.Linq.Enumerable+SelectArrayIterator`2[TSource,TResult].ToArray () (at <83c2e80c632943a485c1e12619e4eddd>:0)
System.Linq.Enumerable.ToArray[TSource] (System.Collections.Generic.IEnumerable`1[T] source) (at <83c2e80c632943a485c1e12619e4eddd>:0)
Shapes.ShapeRendererEditor.OnEnable () (at Assets/Shapes/Scripts/Editor/Components/ShapeRendererEditor.cs:108)
Shapes.DiscEditor.OnEnable () (at Assets/Shapes/Scripts/Editor/Components/DiscEditor.cs:35)</onenable>

MissingReferenceException: The variable m_Targets of GameObjectInspector doesn't exist anymore.
You probably need to reassign the m_Targets variable of the 'GameObjectInspector' script in the inspector. Parameter name: componentOrGameObject
UnityEngine.Object+MarshalledUnityObject.TryThrowEditorNullExceptionObject (UnityEngine.Object unityObj, System.String parameterName) (at <2cc8976df9884fb7bcb48c3f3813f67b>:0)
UnityEngine.Bindings.ThrowHelper.ThrowArgumentNullException (System.Object obj, System.String parameterName) (at <2cc8976df9884fb7bcb48c3f3813f67b>:0)
UnityEditor.PrefabUtility.IsPartOfVariantPrefab (UnityEngine.Object componentOrGameObject) (at <94e1644530894ca4afcc0afbfd6605d3>:0)
UnityEditor.GameObjectInspector.OnEnable () (at <94e1644530894ca4afcc0afbfd6605d3>:0)

Based on the errors, I'm guessing it has something to do with my game spawning prefabs that contain Shapes components in both enabled and disabled states, but that is JUST a guess.