NullReferenceException errors are thrown continuously on creating Brush asset with OpenGLES2 Graphics APIs.

Steps to repro:
1. Create a new project.
2. Change Graphics APIs to OpenGLES2.
3. Right-click on Project Window.
4. Create > Brush.

Actual Result:
NullReferenceException errors are thrown in the console.

Expected Result:
No errors in the console.

Reproducible on:
2020.1.0a12, 2019.3.0b10, 2019.3.0b6.

Working Fine in:
2019.3.0b5.

Environment:
Only on Windows.

Stack trace:
NullReferenceException
UnityEngine.Texture.get_width () (at <4e781ea27afa4779b4c4bcd46aeba67a>:0)
UnityEngine.Texture2D.SetPixels (UnityEngine.Color[] colors) (at <4e781ea27afa4779b4c4bcd46aeba67a>:0)
UnityEditor.Brush.GenerateBrushTexture (UnityEngine.Texture2D mask, UnityEngine.AnimationCurve falloff, System.Single radiusScale, System.Single blackWhiteRemapMin, System.Single blackWhiteRemapMax, System.Boolean invertRemapRange, System.Int32 width, System.Int32 height, System.Boolean isThumbnail) (at <b43e6d4802d64ea8bbdaa0bf64614d3b>:0)
UnityEditor.BrushEditor.OnPreviewGUI (UnityEngine.Rect r, UnityEngine.GUIStyle background) (at <b43e6d4802d64ea8bbdaa0bf64614d3b>:0)
UnityEditor.Editor.OnInteractivePreviewGUI (UnityEngine.Rect r, UnityEngine.GUIStyle background) (at <b43e6d4802d64ea8bbdaa0bf64614d3b>:0)
UnityEditor.ObjectPreview.DrawPreview (UnityEditor.IPreviewable defaultPreview, UnityEngine.Rect previewArea, UnityEngine.Object[] targets) (at <b43e6d4802d64ea8bbdaa0bf64614d3b>:0)
UnityEditor.Editor.DrawPreview (UnityEngine.Rect previewArea) (at <b43e6d4802d64ea8bbdaa0bf64614d3b>:0)
UnityEditor.InspectorWindow.DrawPreviewAndLabels () (at <b43e6d4802d64ea8bbdaa0bf64614d3b>:0)
UnityEngine.UIElements.IMGUIContainer.DoOnGUI (UnityEngine.Event evt, UnityEngine.Matrix4x4 parentTransform, UnityEngine.Rect clippingRect, System.Boolean isComputingLayout, UnityEngine.Rect layoutSize, System.Boolean canAffectFocus) (at <b256487a5e4140809d026a943f161bc2>:0)
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr)