When an user tries to create a list input from 'Properties Assignment', status code 500 error occurs.

Environment

Frankfurt (OOM), Guilin RC0 (OOM), master branch (docker) as of Oct.28

Steps to reproduce

1. Log in as designer (cs0008)
2. Create a VF
3. Add some properties from 'Properties Assignment'
4. Select (check) properties and click 'Create List Input'
5. Enter 'Name' and 'Schema Type', then click 'Save'
6. Status code 500 error occurs
   (message is shown behind create list input modal window)