Address deletion condition when accessing orm object attributes in co…

…ntroller delete_sources. Ensure DeleteSourceDialog is shown even with no sources selected in widgets.py and improve comments.

client/securedrop_client/gui/widgets.py

@@ -553,7 +553,7 @@ def on_action_triggered(self) -> None:
             # The current source selection is continuously received by the controller
             # as the user selects and deselects; here we retrieve the selection
             targets = self.controller.get_selected_sources()
-            if targets:
+            if targets is not None:
                 dialog = DeleteSourceDialog(targets)
                 dialog.accepted.connect(lambda: self.controller.delete_sources(targets))
                 dialog.exec()
@@ -904,6 +904,8 @@ def on_source_changed(self) -> None:
             # One source selected; prepare the conversation widget
             try:
                 source = self.source_list.get_selected_source()
+
+                # Avoid race between user selection and remote deletion
                 if not source:
                     return
 
@@ -1299,6 +1301,7 @@ def schedule_source_management(slice_size: int = slice_size) -> None:
         QTimer.singleShot(1, schedule_source_management)
 
     def get_selected_source(self) -> Optional[Source]:
+        # if len == 0, return None
         if not self.selectedItems():
             return None
 

client/securedrop_client/logic.py

@@ -1035,7 +1035,17 @@ def delete_sources(self, sources: list[db.Source]) -> None:
         the failure handler will display an error.
         """
         for source in sources:
-            job = DeleteSourceJob(source.uuid)
+            try:
+                # Accessing source.uuid requires the source object to be
+                # present in the database.
+                # To avoid passing and referencing orm objects, a simplified
+                # ViewModel layer decoupled from the db that presents data to the API/GUI
+                # would be another possibility.
+                job = DeleteSourceJob(source.uuid)
+            except sqlalchemy.orm.exc.ObjectDeletedError:
+                logger.warning("DeleteSourceJob requested but source already deleted")
+                return
+
             job.success_signal.connect(self.on_delete_source_success)
             job.failure_signal.connect(self.on_delete_source_failure)