EditorGUILayout.GradientField not working properly

I have a little problem with the gradient field in my custom editor window.
The problem is that when I import the script to a project (or I change something in the script) the gradientfields in the editor window just randomly decides that they don't want to work. When I delete the fields from the code and then I readd the exact code it is working again. Is this a bug or what? I'm really frustrated by that, I'm creating an asset, but it's useless if it breaks after importing.

Should show this:

but shows this:


This is the error I get:

NullReferenceException: Object reference not set to an instance of an object

UnityEditor.GradientEditor.GetMaxColorComponent (UnityEngine.Gradient gradient) (at <3e481e8f36eb4d4c8d94b9ba6b2be438>:0)

UnityEditor.GradientEditor.DrawGradientSwatchInternal (UnityEngine.Rect position, UnityEngine.Gradient gradient, UnityEditor.SerializedProperty property, UnityEngine.Color bgColor) (at <3e481e8f36eb4d4c8d94b9ba6b2be438>:0)

UnityEditor.GradientEditor.DrawGradientSwatch (UnityEngine.Rect position, UnityEngine.Gradient gradient, UnityEngine.Color bgColor) (at <3e481e8f36eb4d4c8d94b9ba6b2be438>:0)

UnityEditor.EditorGUI.DoGradientField (UnityEngine.Rect position, System.Int32 id, UnityEngine.Gradient value, UnityEditor.SerializedProperty property, System.Boolean hdr) (at <3e481e8f36eb4d4c8d94b9ba6b2be438>:0)

UnityEditor.EditorGUI.GradientField (UnityEngine.Rect position, UnityEngine.GUIContent label, UnityEngine.Gradient gradient, System.Boolean hdr) (at <3e481e8f36eb4d4c8d94b9ba6b2be438>:0)

UnityEditor.EditorGUI.GradientField (UnityEngine.Rect position, UnityEngine.GUIContent label, UnityEngine.Gradient gradient) (at <3e481e8f36eb4d4c8d94b9ba6b2be438>:0)

UnityEditor.EditorGUI.GradientField (UnityEngine.Rect position, System.String label, UnityEngine.Gradient gradient) (at <3e481e8f36eb4d4c8d94b9ba6b2be438>:0)

UnityEditor.EditorGUILayout.GradientField (System.String label, UnityEngine.Gradient value, UnityEngine.GUILayoutOption[] options) (at <3e481e8f36eb4d4c8d94b9ba6b2be438>:0)

MeshGeneratorWindow.ShowGradientfieldCustomvoidbecauseiDontKnowWhatTodothisshitisbroken (System.String _label, UnityEngine.Gradient _gradient) (at Assets/Mesh Generator Tools/Scripts/MeshGeneratorWindow.cs:290)

MeshGeneratorWindow.OnGUI () (at Assets/Mesh Generator Tools/Scripts/MeshGeneratorWindow.cs:251)

System.Reflection.MonoMethod.Invoke (System.Object obj, System.Reflection.BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) (at <437ba245d8404784b9fbab9b439ac908>:0)

Rethrow as TargetInvocationException: Exception has been thrown by the target of an invocation.

UnityEngine.UIElements.UIR.RenderChain.Render (UnityEngine.Rect viewport, UnityEngine.Matrix4x4 projection, UnityEngine.UIElements.PanelClearFlags clearFlags) (at <b74e373726c44093a12f440dfb8c99b8>:0)

UnityEngine.UIElements.UIRRepaintUpdater.DrawChain (UnityEngine.Rect viewport, UnityEngine.Matrix4x4 projection) (at <b74e373726c44093a12f440dfb8c99b8>:0)

UnityEngine.UIElements.UIRRepaintUpdater.Update () (at <b74e373726c44093a12f440dfb8c99b8>:0)

UnityEngine.UIElements.VisualTreeUpdater.UpdateVisualTreePhase (UnityEngine.UIElements.VisualTreeUpdatePhase phase) (at <b74e373726c44093a12f440dfb8c99b8>:0)

UnityEngine.UIElements.Panel.UpdateForRepaint () (at <b74e373726c44093a12f440dfb8c99b8>:0)

UnityEngine.UIElements.Panel.Repaint (UnityEngine.Event e) (at <b74e373726c44093a12f440dfb8c99b8>:0)

UnityEngine.UIElements.UIElementsUtility.DoDispatch (UnityEngine.UIElements.BaseVisualElementPanel panel) (at <b74e373726c44093a12f440dfb8c99b8>:0)

UnityEngine.UIElements.UIElementsUtility.ProcessEvent (System.Int32 instanceID, System.IntPtr nativeEventPtr) (at <b74e373726c44093a12f440dfb8c99b8>:0)

UnityEngine.GUIUtility.ProcessEvent (System.Int32 instanceID, System.IntPtr nativeEventPtr) (at <817eebdd70f8402280b9cb11fff8b976>:0)

 

I'm getting this same issue in Unity 2021.3.11 LTS