If you save an Editor Layout with a blank name e.g. a single space, the following warning will be displayed in the console:

Menu Window/Layouts/ can't be checked because it doesn't exist
UnityEditor.EditorApplication:Internal_CallDelayFunctions()

This warning will also occur whenever a project is loaded.

1. Open Unity
2. Create a project with any settings
3. Go to Layout > Save Layout...
4. Enter a single space character as the layout name
5. Save the layout

Expected Result:
The layout is saved successfully without any warnings or errors.

Actual Result:
A warning is produced.

Tested on Windows.

Occurs on 2019.3.0a1, 2019.2.0a7

Does not occur on 2019.2.0a6