Correcting a small bug

I though «addMode» meant «call from addcard window». Instead, to know
whether parent is addcard, I check whether it has attribute deckChooser

aqt/clayout.py

@@ -61,7 +61,9 @@ class CardLayout(QDialog):
         self.setFocus()
 
     def redraw(self):
-        did = self.parent.deckChooser.selectedId() if self.addMode else None
+        did = None
+        if hasattr(self.parent,"deckChooser"):
+                did = self.parent.deckChooser.selectedId()
         self.cards = self.col.previewCards(self.note, 2, did = did)
         idx = self.ord
         if idx >= len(self.cards):