There is a problem when I import file google-services.json that holds settings for Firebase project in Unity.
When importing file an error occurs (listed below) and no other postprocessors will run.
As I remove inheritance for class "SpineEditorUtilities : AssetPostprocessor" Firebase SDK process this json normally.
Is there any way to fix this issue?

KeyNotFoundException: The given key was not present in the dictionary.
System.Collections.Generic.Dictionary`2[System.String,System.Object].get_Item (System.String key) (at /Users/builduser/buildslave/mono/build/mcs/class/corlib/System.Collections.Generic/Dictionary.cs:150)
Spine.Unity.Editor.SpineEditorUtilities.IsValidSpineData (UnityEngine.TextAsset asset) (at Assets/spine-unity/Editor/SpineEditorUtilities.cs:955)
Spine.Unity.Editor.SpineEditorUtilities.ImportSpineContent (System.String[] imported, Boolean reimport) (at Assets/spine-unity/Editor/SpineEditorUtilities.cs:329)
Spine.Unity.Editor.SpineEditorUtilities.OnPostprocessAllAssets (System.String[] imported, System.String[] deleted, System.String[] moved, System.String[] movedFromAssetPaths) (at Assets/spine-unity/Editor/SpineEditorUtilities.cs:308)
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 C:/buildslave/unity/build/Editor/Mono/AssetPostprocessor.cs:27)