On creating Preset of the "SpriteSkin" component editor throw NullReferenceException, refer to the attached video.

Steps to repro:
1. Create a new project
2. Windows > Package Manager > 2D Animation > Install
3. Hierarchy > right-click > Create Empty
4. Inspector > Add Component > 2D Animation > Sprite Skin > Add
5. Create Preset Sprite Skin.
6. Project > Sprite Skin Preset >Click

Actual Result:
NullReferenceException is thrown on creating the Preset of the "SpriteSkin" component.

Expected Result:
Preset of the "SpriteSkin" component created gracefully.

Reproducible in:
2020.2.0a15 with Package Version 5.0.0
2020.2.0a14, 2020.1.0b12 with Package Version 4.2.4, 4.2.2

Working fine in:
2020.2.0a11, 2020.1.0b9, 2020.1.0a13 with Package Version: 4.2.1.

Environment:
Windows 10 & macOS 10.14

Stack Trace:
NullReferenceException: Object reference not set to an instance of an object
UnityEngine.U2D.Animation.SpriteSkinUtility.Validate (UnityEngine.U2D.Animation.SpriteSkin spriteSkin) (at Library/PackageCache/com.unity.2d.animation@5.0.0/Runtime/SpriteSkinUtility.cs:29)
UnityEngine.U2D.Animation.SpriteSkin.get_isValid () (at Library/PackageCache/com.unity.2d.animation@5.0.0/Runtime/SpriteSkin.cs:395)
UnityEngine.U2D.Animation.SpriteSkin.CacheValidFlag () (at Library/PackageCache/com.unity.2d.animation@5.0.0/Runtime/SpriteSkin.cs:150)
UnityEngine.U2D.Animation.SpriteSkin.Reset () (at Library/PackageCache/com.unity.2d.animation@5.0.0/Runtime/SpriteSkin.cs:157)
UnityEditor.Presets.PresetEditor:OnEnable()