Typeerror: Cannot Read Property 'properties' Of Undefined

I have a Node.js/Geddy app which was working untill a few minutes ago. Now, when I try to run it, I get the following error: I have many models, but for one of them, I get this e

Solution 1:

Finally!!! Thanks to THIS I've found out that it was a hasOne() or has Many() with a wrong parameter.