ApplicationOutputPane: Add missing handling of runControl being nullptr

Change-Id: I8f7b5f90bfa7389df55b42910ba245ad78ef5bc6
Reviewed-by: Tobias Hunger <tobias.hunger@qt.io>

src/plugins/projectexplorer/appoutputpane.cpp

@@ -582,6 +582,7 @@ void AppOutputPane::closeTab(int tabIndex, CloseTabMode closeTabMode)
     m_tabWidget->removeTab(tabIndex);
     delete window;
 
+    if (runControl)
         runControl->initiateFinish(); // Will self-destruct.
     m_runControlTabs.removeAt(index);
     updateCloseActions();