If admin session has timed out, uploading an image to media library incorrectly returns "Server cannot process this image" error, along with info about image sizes

[bluesix]

In the backend, if a user session expires (cookie expires) whilst on the media library page, and a user tries to upload an image in the media library, the server returns the standard "The server cannot process the image. This can happen if the server is busy or does not have enough resources to complete the task. Uploading a smaller image may help. Suggested maximum size is 2560 pixels." when it should either return authentication error-related text or kick the user out to the dashboard login page.