Reproduction steps:
1. Open the attached project (ScriptableObjectCreateAssetMenuIssue.zip);
2. Go to the AssetMenu;
3. Try to create an instance of "AbstractScriptableObject".
4. Observe the error message in console that says:
"Instance of AbstractScriptableObject couldn't be created.
The script class needs to derive from ScriptableObject."

Expected result: The error message explains that you can not create instances of abstract classes.
Actual result: The error message warns that the class needs to derive from ScriptableObject.

Reproduced on: 5.3.6p8, 5.4.2p4, 5.5.0f2, 5.6.0a3.