To reproduce

1. Install WebEdit 2.1 into any version of 32-bit Notepad++

2. After installation, copy WebEdit.ini from the plugin's Config folder into
   $(LOCAL_NPP_DIR)\plugins\Config (portable) or %AppData%\Notepad++\plugins\Config (full installation)

3. Expand the plugin menu and select WebEdit

4. Notice that empty menu slots are disabled (light gray):

   

5. Open any file in the editor

6. Close the file

7. Repeat step 3.

8. Notice that every menu slot is now enabled:

   

If any command with a title of WebEdit Slot ... is clicked, the program crashes.