Front-end does not correctly react to upload errors

Uploading PDFs which exceed the maximum file size in the Quiz Editor block further behaviour. The exception thrown when the maximum file size is exceeded can be found below.

019-05-06 15:34:11.967 ERROR 7466 --- [nio-8080-exec-5] o.a.c.c.C.[.[.[/].[dispatcherServlet] : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is org.springframework.web.multipart.MaxUploadSizeExceededException: Maximum upload size exceeded; nested exception is java.lang.IllegalStateException: org.apache.tomcat.util.http.fileupload.FileUploadBase$SizeLimitExceededException: the request was rejected because its size (28932497) exceeds the configured maximum (26214400)] with root cause

The expected behaviour is that the front-end will show an error and then let the organizer reupload his/her file. At this moment, the front-end will shortly show an error and then go back to the progress bar that says "PDF uploading...", while nothing is actually happening at that point.

Tasks:

Ensure a correct error message is shown to the organizer when an upload fails.
Ensure the upload component returns back to the correct state after a failed upload.

Edited May 06, 2019 by Remco de Man

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information