qmljseditor: fix crash at shutdown

Change-Id: Ifae7ec5f378c0b2d3e667bd26a509fbcbefadecf
Reviewed-by: Thomas Hartmann <thomas.hartmann@qt.io>
Reviewed-by: Kai Koehne <kai.koehne@qt.io>

src/plugins/qmljseditor/qmljseditorplugin.cpp

@@ -110,6 +110,7 @@ QmlJSEditorPlugin::QmlJSEditorPlugin()
 
 QmlJSEditorPlugin::~QmlJSEditorPlugin()
 {
+    delete QmlJS::Icons::instance(); // delete object held by singleton
     delete d;
     d = nullptr;
     m_instance = nullptr;
@@ -226,8 +227,6 @@ void QmlJSEditorPlugin::extensionsInitialized()
 
 ExtensionSystem::IPlugin::ShutdownFlag QmlJSEditorPlugin::aboutToShutdown()
 {
-    delete QmlJS::Icons::instance(); // delete object held by singleton
-
     return IPlugin::aboutToShutdown();
 }