Error: widgets.js:2 The store was queried with a [string] but the entity id is a [undefined]

Description

Steps to reproduce:

1. Edit the start page on the Alloy sample site.
2. Change the logotype image.
OR
1. Create a Contact block (or anything with an image property; the goal is to have an empty image property)
2. Open the Select Image dialog from the Image property.

Expected:
No error in the console.

Actual:
The console shows this error:
"widgets.js:2 The store was queried with a [string] but the entity id is a [undefined]"