If you right click to open the context menu while editing a shortcut, then click outside the context menu to dismiss it, an error will occur in the console:

Drags can only be started from MouseDown or MouseDrag events
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr)

1. Open Unity
2. Open the attached project
3. Go to Edit > Shortcuts
4. Double click any shortcut to edit it
5. Right click in the text input field to open the context menu
6. Left click outside the context menu to dismiss it

Expected Result:
The context menu is closed without any errors or warnings.

Actual Result:
An error appears in the console.

Tested on Windows.

Occurs in 2019.1.0a4, 2019.1.0b11, 2019.2.0a11, 2021.020a10