Cannot return null for non-nullable field & cannot read properties of undefined (reading 'reply')

I don’t understand why I am getting these 2 errors. First of all, whenever I try to fetch all the cars from my DB (MySQL if it bears any relevance) I am expecting to only see:

    "data": null

but I also get the error you guys see in the top-left corner:

"errors": [
      "message": "Cannot read properties of undefined (reading 'reply')",

Besides that, I get the error regarding the ID you can see bottom-right. Why is that? I used the “@PrimaryGeneratedColumn” decorator, so shouldn’t that implicitly handle assigning an ID to every object I try to insert in my “cars” table?

Also, where precisely should I look (which file) so that I can relate the line&column in “locations” with the error?
I hope I included everything needed; if not, I could provide more info.
Thank you in advance!