Steps to Reproduce:
- Create a page that contains at least one image with no thumb or similar file specification, e.g.,
[[File:Example.jpg|Here's an image.]]
- Open the page in VisualEditor.
- Select the image and open the image inspector.
- Try to get out of the image inspector.
The "Advanced settings" pane in the image inspector has a spinning death spiral and the error message, "Size values are invalid. Could not retrieve original file size."
The X to close the image inspector does not respond.
This was first reported by Magioladitis for the pdf's listed here: https://el.wikipedia.org/w/index.php?oldid=4650532#.CE.94.CE.B9.CE.B1.CE.BB.CE.AD.CE.BE.CE.B5.CE.B9.CF.82