Check for valid _foregroundProcessInfo to prevent crash
Summary:
In Session::getUrl() check that _foregroundProcessInfo is valid before
tyring to access its members.
I couldn't reproduce the crash from the BR, but it is logical to call
isValid() before accessing any ProcessInfo object members.
BUG: 391447
Reviewers: Konsole, hindenburg
Reviewed By: Konsole, hindenburg
Subscribers: Konsole
Tags: Konsole
Differential Revision: https://phabricator.kde.org/D12175