QmlDesigner: clear texteditor view statusbar

- when puppet is restarted
 - when the view is attached (switching document, switching mode)

Change-Id: I06a4acf78a18b893bca9f7cd3d2bae74dc3459aa
Reviewed-by: Thomas Hartmann <thomas.hartmann@qt.io>

src/plugins/qmldesigner/components/texteditor/texteditorview.cpp

@@ -93,6 +93,7 @@ TextEditorView::~TextEditorView()
 void TextEditorView::modelAttached(Model *model)
 {
     Q_ASSERT(model);
+    m_widget->clearStatusBar();
 
     AbstractView::modelAttached(model);
 

src/plugins/qmldesigner/designercore/instances/nodeinstanceview.cpp

@@ -205,6 +205,7 @@ void NodeInstanceView::restartProcess()
     if (rootNodeInstance().isValid())
         rootNodeInstance().setError({});
     emitInstanceErrorChange({});
+    emitDocumentMessage({}, {});
 
     if (m_restartProcessTimerId)
         killTimer(m_restartProcessTimerId);

src/plugins/qmldesigner/designercore/model/abstractview.cpp

@@ -598,7 +598,8 @@ void AbstractView::emitDocumentMessage(const QString &error)
 
 void AbstractView::emitDocumentMessage(const QList<DocumentMessage> &errors, const QList<DocumentMessage> &warnings)
 {
-    model()->d->setDocumentMessages(errors, warnings);
+    if (model())
+        model()->d->setDocumentMessages(errors, warnings);
 }
 
 void AbstractView::emitCustomNotification(const QString &identifier)