NullReferenceException

i bought this asset today and when trying to create a shape (whatever it is, line, rectangle etc...) i got NullReferenceException.

details:

NullReferenceException: Object reference not set to an instance of an object
Shapes.ShapesColorFieldDrawer.OnGUI (UnityEngine.Rect position, UnityEditor.SerializedProperty property, UnityEngine.GUIContent label) (at Assets/Shapes/Scripts/Editor/Utils/ShapesColorFieldDrawer.cs:13)
UnityEditor.PropertyDrawer.OnGUISafe (UnityEngine.Rect position, UnityEditor.SerializedProperty property, UnityEngine.GUIContent label) (at <0cde216a590a4d6fbc3d7db7ac203c5d>:0)
UnityEditor.PropertyHandler.OnGUI (UnityEngine.Rect position, UnityEditor.SerializedProperty property, UnityEngine.GUIContent label, System.Boolean includeChildren, UnityEngine.Rect visibleArea) (at <0cde216a590a4d6fbc3d7db7ac203c5d>:0)
UnityEditor.PropertyHandler.OnGUI (UnityEngine.Rect position, UnityEditor.SerializedProperty property, UnityEngine.GUIContent label, System.Boolean includeChildren) (at <0cde216a590a4d6fbc3d7db7ac203c5d>:0)
UnityEditor.PropertyHandler.OnGUILayout (UnityEditor.SerializedProperty property, UnityEngine.GUIContent label, System.Boolean includeChildren, UnityEngine.GUILayoutOption[] options) (at <0cde216a590a4d6fbc3d7db7ac203c5d>:0)
UnityEditor.EditorGUILayout.PropertyField (UnityEditor.SerializedProperty property, UnityEngine.GUIContent label, System.Boolean includeChildren, UnityEngine.GUILayoutOption[] options) (at <0cde216a590a4d6fbc3d7db7ac203c5d>:0)
UnityEditor.EditorGUILayout.PropertyField (UnityEditor.SerializedProperty property, UnityEngine.GUILayoutOption[] options) (at <0cde216a590a4d6fbc3d7db7ac203c5d>:0)
Shapes.ShapeRendererEditor.PropertyFieldColor () (at Assets/Shapes/Scripts/Editor/Components/ShapeRendererEditor.cs:230)
Shapes.LineEditor.OnInspectorGUI () (at Assets/Shapes/Scripts/Editor/Components/LineEditor.cs:66)
UnityEditor.UIElements.InspectorElement+<>c__DisplayClass59_0.b__0 () (at :0)