catch attempts to nest under a filtered deck; don't show traceback

ftl/core/errors.ftl

@@ -1,4 +1,4 @@
 errors-invalid-input-empty = Invalid input.
 errors-invalid-input-details = Invalid input: { $details }
 errors-parse-number-fail = A number was invalid or out of range.
-errors-filtered-parent-deck = Invalid deck name: Filtered decks cannot be parent decks.
+errors-filtered-parent-deck = Filtered decks can not have child decks.

qt/aqt/deckbrowser.py

@@ -287,7 +287,11 @@ class DeckBrowser:
         self._renderPage(reuse=True)
 
     def _handle_drag_and_drop(self, source: int, target: int) -> None:
-        self.mw.col.decks.drag_drop_decks([source], target)
+        try:
+            self.mw.col.decks.drag_drop_decks([source], target)
+        except Exception as e:
+            showWarning(str(e))
+            return
         gui_hooks.sidebar_should_refresh_decks()
         self.show()
 

qt/aqt/sidebar.py

@@ -472,7 +472,11 @@ class SidebarTreeView(QTreeView):
 
         def on_done(fut: Future) -> None:
             self.browser.model.endReset()
-            fut.result()
+            try:
+                fut.result()
+            except Exception as e:
+                showWarning(str(e))
+                return
             self.refresh()
             self.mw.deckBrowser.refresh()
 

rslib/src/decks/mod.rs

@@ -605,6 +605,9 @@ impl Collection {
             let mut target_name = None;
             if let Some(target) = target {
                 if let Some(target) = col.storage.get_deck(target)? {
+                    if target.is_filtered() {
+                        return Err(AnkiError::DeckIsFiltered);
+                    }
                     target_deck = target;
                     target_name = Some(target_deck.name.as_str());
                 }