PE: Avoid possible nullptr access

Change-Id: Ib96ce9763dd9710cc4365978241d5d1d3ac1c0db
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>

src/plugins/projectexplorer/targetsettingspanel.cpp

@@ -161,6 +161,9 @@ TargetSetupPageWrapper::TargetSetupPageWrapper(Project *project)
 
 void TargetSetupPageWrapper::updateNoteText()
 {
+    if (!m_targetSetupPage)
+        return;
+
     Kit *k = KitManager::defaultKit();
 
     QString text;