Throw an extension when upload without upload comment

* Casts uploadComment to string before writing in DB
4 jobs for bugfix/throw-exception-for-empty-upload-comment in 6 minutes and 27 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Test
passed #8938
test:php

00:00:20

passed #8937
test:unit

00:01:57

 
  Build
passed #8939
build

00:01:38

 
  Layout
passed #8940
layout

00:02:51