"Could not determine preset file location type" error is thrown when a swatch preset library is created with name starting with "/". After this, error is thrown everytime on opening material colour palette. Refer the attached video

Steps to reproduce:
1) Create a new project
2) Create a new material
3) Click on the Color palette next to Albedo
4) Swatches > Create a new Library
5) Create a library with name starting with "/"

Actual result: "Could not determine preset file location type" error is thrown.

Expected result: No Error should be thrown

Occurring on: 2020.2.0a14, 2020.1.0b12, 2019.4.0f1, 2019.2.9f1, 2018.4.15f1

Environment: Both Windows and Mac

Stack trace:
Could not determine preset file location type /1234567
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr) (at C:/buildslave/unity/build/Modules/IMGUI/GUIUtility.cs:179)