Before testing this bug, it may be necessary to remove some applications to reproduce situation when only applications with no documentation are present in a menu group.
On my test machine, I have only 'LibreOffice Math' in 'Science' group, and around 4 applications in 'Development' group, and none of these applications have information about
documentation present at all or in way that khelpcenter can detect and process.
Thus, when I open menu item Application Manuals -> Science or Development, it is completely empty.
With this change all such empty items should be hidden instead.