Custom Error 404 in /content/images

Hi i configured a custom theme with a error 404 template following the error context instructions:

it works fine in almost all the non existent urls of the page but for some reason in the url: /content/images it doesnt show the custom error 404 template, instead it show a white page with the text 404 Image not found.

i supose this problem is related to that fact that /content/images is a folder y the ghost folder

its some aditional configuration needed in order to show my custom error page in this url ?