When a custom inspector targetting Texture2D, Cubemap or Texture3D is present in the project, the texture importer inspector of these assets throws errors when they are displayed in the inspector window.

Stacktrace of the error:
InvalidCastException: Specified cast is not valid.
UnityEditor.TextureImporterInspector.get_textureInspector () (at <280242b5f32c446482b2e1fcdf7e6d80>:0)
UnityEditor.TextureImporterInspector.DrawPreview (UnityEngine.Rect previewArea) (at <280242b5f32c446482b2e1fcdf7e6d80>:0)
UnityEditor.PropertyEditor.DrawPreviewAndLabels () (at <280242b5f32c446482b2e1fcdf7e6d80>:0)
UnityEngine.UIElements.IMGUIContainer.DoOnGUI (UnityEngine.Event evt, UnityEngine.Matrix4x4 parentTransform, UnityEngine.Rect clippingRect, System.Boolean isComputingLayout, UnityEngine.Rect layoutSize, System.Action onGUIHandler, System.Boolean canAffectFocus) (at <b50b24924f4d442fb2face92883f4dc2>:0)
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr, Boolean&)

Here's an example of custom editor that causes the error:
```
[CustomEditor(typeof(Texture2D), false)]
class MixtureInspectorTexture2D : MixtureEditor
{
public override bool HasPreviewGUI() => true;
}
```

Repro steps:
- Download the repro project
- Select the texture A in the Assets folder
- Observe errors in the console, like in the attached gif.

Note that the issue doesn't repro on 2020.2. Tested on Unity 2021.1 and 2021.2.