Fix displaying remaining projects by closing one in tabbed or sub-window view mode

JIRA issue: https://its.cern.ch/jira/browse/SUS-1630

The problem was that if you closed the project directly from the window, it was not properly deleted and there was no current sub-window, as explained here. So you ended up in the else branch that doesn't exist. Now, regardless of how you close a project, if there are other projects open, the next one will be shown without changing the view mode.