Adding/importing a sprite to the project generates three errors.

- create a new 2D project
- drag an image file into the Project Assets or create a new 2D sprite in the Project Assets
- observe the error messages that appear in the Console

Matrix stack full depth reached
UnityEditor.AssetPreviewUpdater:CreatePreviewForAsset(Object, Object[], String)
UnityEditorInternal.InternalEditorUtility:ProjectWindowDrag(HierarchyProperty, Boolean)
UnityEditor.DockArea:OnGUI()

Exception: GL.Begin can only be invoked during a repaint event
UnityEngine.GL.Begin (Int32 mode) (at C:/buildslave/unity/build/artifacts/generated/common/runtime/GraphicsBindings.gen.cs:2414)
UnityEditor.SpriteInspector.BuildPreviewTexture (Int32 width, Int32 height, UnityEngine.Sprite sprite, UnityEngine.Material spriteRendererMaterial, Boolean isPolygon) (at C:/buildslave/unity/build/Editor/Mono/Inspector/SpriteFrameInspector.cs:236)
UnityEditor.SpriteInspector.RenderStaticPreview (System.String assetPath, UnityEngine.Object[] subAssets, Int32 width, Int32 height) (at C:/buildslave/unity/build/Editor/Mono/Inspector/SpriteFrameInspector.cs:284)
UnityEditor.AssetPreviewUpdater.CreatePreviewForAsset (UnityEngine.Object obj, UnityEngine.Object[] subAssets, System.String assetPath) (at C:/buildslave/unity/build/Editor/Mono/AssetPreviewUpdater.cs:33)
UnityEditorInternal.InternalEditorUtility:ProjectWindowDrag(HierarchyProperty, Boolean)
UnityEditor.DockArea:OnGUI()

Matrix stack full depth reached
UnityEditor.DockArea:OnGUI()