unityエラー Operation is not valid due to the current state of the object

インスペクタからAudioClipを設定しようとしたところ以下のエラーが発生。
InvalidOperationException: Operation is not valid due to the current state of the object
System.Collections.Generic.Stack`1[System.Boolean].Pop ()
UnityEditor.EditorGUI.EndDisabledGroup () (at /Users/builduser/buildslave/unity/build/Editor/Mono/EditorGUI.cs:211)
UnityEditor.EditorGUI+DisabledGroupScope.CloseScope () (at /Users/builduser/buildslave/unity/build/Editor/Mono/EditorGUI.cs:197)
UnityEngine.GUI+Scope.Dispose ()
UnityEditor.Editor.OptimizedInspectorGUIImplementation (Rect contentRect) (at /Users/builduser/buildslave/unity/build/artifacts/generated/common/editor/EditorBindings.gen.cs:234)
UnityEditor.GenericInspector.OnOptimizedInspectorGUI (Rect contentRect) (at /Users/builduser/buildslave/unity/build/Editor/Mono/Inspector/GenericInspector.cs:33)
UnityEditor.InspectorWindow.DrawEditor (UnityEditor.Editor editor, Int32 editorIndex, Boolean rebuildOptimizedGUIBlock, System.Boolean& showImportedObjectBarNext, UnityEngine.Rect& importedObjectBarRect) (at /Users/builduser/buildslave/unity/build/Editor/Mono/Inspector/InspectorWindow.cs:1211)
UnityEditor.InspectorWindow.DrawEditors (UnityEditor.Editor[] editors) (at /Users/builduser/buildslave/unity/build/Editor/Mono/Inspector/InspectorWindow.cs:1028)
UnityEditor.InspectorWindow.OnGUI () (at /Users/builduser/buildslave/unity/build/Editor/Mono/Inspector/InspectorWindow.cs:352)
System.Reflection.MonoMethod.Invoke (System.Object obj, BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) (at /Users/builduser/buildslave/mono/build/mcs/class/corlib/System.Reflection/MonoMethod.cs:222)

TypeLoadException: Could not load type 'ResolverVer1_1'.
System.Type.GetType (System.String typeName, Boolean throwOnError) (at /Users/builduser/buildslave/mono/build/mcs/class/corlib/System/Type.cs:471)
GooglePlayServices.PlayServicesResolver.get_Resolver () (at Assets/PlayServicesResolver/Editor/PlayServicesResolver.cs:96)
GooglePlayServices.PlayServicesResolver.OnPostprocessAllAssets (System.String[] importedAssets, System.String[] deletedAssets, System.String[] movedAssets, System.String[] movedFromAssetPaths) (at Assets/PlayServicesResolver/Editor/PlayServicesResolver.cs:117)
System.Reflection.MonoMethod.Invoke (System.Object obj, BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) (at /Users/builduser/buildslave/mono/build/mcs/class/corlib/System.Reflection/MonoMethod.cs:222)
Rethrow as TargetInvocationException: Exception has been thrown by the target of an invocation.
System.Reflection.MonoMethod.Invoke (System.Object obj, BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) (at /Users/builduser/buildslave/mono/build/mcs/class/corlib/System.Reflection/MonoMethod.cs:232)
System.Reflection.MethodBase.Invoke (System.Object obj, System.Object[] parameters) (at /Users/builduser/buildslave/mono/build/mcs/class/corlib/System.Reflection/MethodBase.cs:115)
UnityEditor.AssetPostprocessingInternal.PostprocessAllAssets (System.String[] importedAssets, System.String[] addedAssets, System.String[] deletedAssets, System.String[] movedAssets, System.String[] movedFromPathAssets) (at /Users/builduser/buildslave/unity/build/Editor/Mono/AssetPostprocessor.cs:27)
UnityEditor.AssetDatabase:Refresh()
GooglePlayGames.Editor.GPGSUpgrader:.cctor() (at Assets/GooglePlayGames/Editor/GPGSUpgrader.cs:102)
UnityEditor.EditorAssemblies:SetLoadedEditorAssemblies(Assembly[])

原因

インスペクタのGUIに不具合が起きている。

解決方法

該当スクリプトをインスペクタで使用しない。
audioclipをスクリプトから読み込ませることにしました。