Debugger: Fix exit crash in Debug-Mode.

Acked-By: hjk

src/plugins/coreplugin/outputpane.cpp

@@ -74,8 +74,11 @@ OutputPanePlaceHolder::OutputPanePlaceHolder(Core::IMode *mode, QSplitter* paren
 OutputPanePlaceHolder::~OutputPanePlaceHolder()
 {
     if (d->m_current == this) {
-        Internal::OutputPaneManager::instance()->setParent(0);
-        Internal::OutputPaneManager::instance()->hide();
+        // FIXME: Prevent exit crash in debug mode.
+        if (Internal::OutputPaneManager *om = Internal::OutputPaneManager::instance()) {
+            om->setParent(0);
+            om->hide();
+        }
     }
 }