8e4f9d5173
The URL used for the generated request was `/ckeditor/pictures&responseType=json`. This is a known issue in the ckeditor gem, and it's suggested to add a `?` at the end of the URL in order to fix it. I haven't added a test for this case since simulating dropping a file in the browser with Selenium/Capybara seems to be quite tricky and I haven't found a solution guaranteed to correctly emulate what users do.