-UnityEngine.ExitGUIException error is thrown on opening color palette window in the Material Inspector.
-Also occurs on openening texture asset selector window.

Steps to repro:
1. Create a new HDRP template Project.
2. Project Window > Right Click > Material.
3. Select Material > Inspector > Surface Input.
4. Base Map > Click to open Color Palette window.

Actual Result:
UnityEngine.ExitGUIException error is thrown in the console.

Expected Result:
No errors in the console.

Reproducible in:
2021.2.0a2, 2021.1.0b3, 2021.1.0a10 with Package Manager 11.0.0.

Working Fine in:
2021.1.0a9 Package Version 10.2.2.

Environment:
Occurring on Windows 10 & Mac 10.15.

Stack trace:
UnityEngine.ExitGUIException: Exception of type 'UnityEngine.ExitGUIException' was thrown.
at UnityEngine.GUIUtility.ExitGUI () [0x00006] in <df88399a35f0499085499d10ca7e0e5d>:0
at UnityEditor.EditorGUI.DoColorField (UnityEngine.Rect position, System.Int32 id, UnityEngine.Color value, System.Boolean showEyedropper, System.Boolean showAlpha, System.Boolean hdr) [0x00119] in <506e8f90527a4ca99baf3418ceee7a30>:0
at UnityEditor.EditorGUI.ColorField (UnityEngine.Rect position, UnityEngine.GUIContent label, UnityEngine.Color value, System.Boolean showEyedropper, System.Boolean showAlpha, System.Boolean hdr) [0x00016] in <506e8f90527a4ca99baf3418ceee7a30>:0
at UnityEditor.MaterialEditor.ColorPropertyInternal (UnityEngine.Rect position, UnityEditor.MaterialProperty prop, UnityEngine.GUIContent label) [0x0002a] in <506e8f90527a4ca99baf3418ceee7a30>:0
at UnityEditor.MaterialEditor.DefaultShaderPropertyInternal (UnityEngine.Rect position, UnityEditor.MaterialProperty prop, UnityEngine.GUIContent label) [0x0004e] in <506e8f90527a4ca99baf3418ceee7a30>:0
at UnityEditor.MaterialEditor.ShaderPropertyInternal (UnityEngine.Rect position, UnityEditor.MaterialProperty prop, UnityEngine.GUIContent label) [0x00057] in <506e8f90527a4ca99baf3418ceee7a30>:0
at UnityEditor.MaterialEditor.ShaderProperty (UnityEngine.Rect position, UnityEditor.MaterialProperty prop, UnityEngine.GUIContent label, System.Int32 labelIndent) [0x0002b] in <506e8f90527a4ca99baf3418ceee7a30>:0
at UnityEditor.MaterialEditor.ShaderProperty (UnityEngine.Rect position, UnityEditor.MaterialProperty prop, UnityEngine.GUIContent label) [0x00001] in <506e8f90527a4ca99baf3418ceee7a30>:0
at UnityEditor.MaterialEditor.ShaderProperty (UnityEngine.Rect position, UnityEditor.MaterialProperty prop, System.String label) [0x0000a] in <506e8f90527a4ca99baf3418ceee7a30>:0
at UnityEditor.MaterialEditor.ExtraPropertyAfterTexture (UnityEngine.Rect r, UnityEditor.MaterialProperty property) [0x00058] in <506e8f90527a4ca99baf3418ceee7a30>:0
at UnityEditor.MaterialEditor.TexturePropertySingleLine (UnityEngine.GUIContent label, UnityEditor.MaterialProperty textureProp, UnityEditor.MaterialProperty extraProperty1, UnityEditor.MaterialProperty extraProperty2) [0x00073] in <506e8f90527a4ca99baf3418ceee7a30>:0
at UnityEditor.MaterialEditor.TexturePropertySingleLine (UnityEngine.GUIContent label, UnityEditor.MaterialProperty textureProp, UnityEditor.MaterialProperty extraProperty1) [0x00001] in <506e8f90527a4ca99baf3418ceee7a30>:0
at UnityEditor.Rendering.HighDefinition.EmissionUIBlock.DoEmissiveTextureProperty (UnityEditor.MaterialProperty color) [0x00000] in E:\Setup\Unity 2021.1.0b2\Editor\Data\Resources\PackageManager\BuiltInPackages\com.unity.render-pipelines.high-definition\Editor\Material\UIBlocks\EmissionUIBlock.cs:279
at UnityEditor.Rendering.HighDefinition.EmissionUIBlock.DrawEmissionGUI () [0x00038] in E:\Setup\Unity 2021.1.0b2\Editor\Data\Resources\PackageManager\BuiltInPackages\com.unity.render-pipelines.high-definition\Editor\Material\UIBlocks\EmissionUIBlock.cs:156
at UnityEditor.Rendering.HighDefinition.EmissionUIBlock.OnGUI () [0x0002b] in E:\Setup\Unity 2021.1.0b2\Editor\Data\Resources\PackageManager\BuiltInPackages\com.unity.render-pipelines.high-definition\Editor\Material\UIBlocks\EmissionUIBlock.cs:121
at UnityEditor.Rendering.HighDefinition.MaterialUIBlockList.OnGUI (UnityEditor.MaterialEditor materialEditor, UnityEditor.MaterialProperty[] properties) [0x0002a] in E:\Setup\Unity 2021.1.0b2\Editor\Data\Resources\PackageManager\BuiltInPackages\com.unity.render-pipelines.high-definition\Editor\Material\UIBlocks\MaterialUIBlockList.cs:62
UnityEngine.GUIUtility:ProcessEvent (int,intptr,bool&)