Fix AssetViewer instance to the same one

Signed-off-by: Loren Eteval <loren.eteval@proton.me>

Furious/Widget/EditRouting.py

@@ -306,7 +306,7 @@ class ImportAssetFileAction(Action):
         super().__init__(_('Import Asset File...'), **kwargs)
 
     def triggeredCallback(self, checked):
-        self.parent().assetViewer.show()
+        APP().editRoutingWidget.assetViewer.show()
 
 
 def questionFastReconnect(saveConfInfo):
@@ -528,8 +528,6 @@ class RoutingEditor(Translatable, SupportConnectedCallback, QMainWindow):
         else:
             self.setWindowIcon(bootstrapIcon('rocket-takeoff-window.svg'))
 
-        self.assetViewer = AssetViewerWidget()
-
         # MessageBox
         self.questionSaveBox = QuestionSaveBox(
             icon=MessageBox.Icon.Question, parent=self