refactor: Improve indexing notification handling and return values

- Enhanced error handling in the indexing process to differentiate between actual failures and cases where no new documents are processed.
- Updated notification messages to reflect the status accurately, including a message for when no new items are synced.
- Standardized return values across various indexer tasks to return `None` on success, simplifying logging and error management.

surfsense_backend/app/tasks/connector_indexers/discord_indexer.py

@@ -549,7 +549,7 @@ async def index_discord_messages(
         logger.info(
             f"Discord indexing completed: {documents_indexed} new messages, {documents_skipped} skipped"
         )
-        return documents_indexed, result_message
+        return documents_indexed, None  # Return None on success (result_message is for logging only)
 
     except SQLAlchemyError as db_error:
         await session.rollback()

surfsense_backend/app/tasks/connector_indexers/notion_indexer.py

@@ -464,7 +464,7 @@ async def index_notion_pages(
         # Clean up the async client
         await notion_client.close()
 
-        return total_processed, result_message
+        return total_processed, None  # Return None on success (result_message is for logging only)
 
     except SQLAlchemyError as db_error:
         await session.rollback()

surfsense_backend/app/tasks/connector_indexers/slack_indexer.py

@@ -413,7 +413,7 @@ async def index_slack_messages(
         logger.info(
             f"Slack indexing completed: {documents_indexed} new channels, {documents_skipped} skipped"
         )
-        return total_processed, result_message
+        return total_processed, None  # Return None on success (result_message is for logging only)
 
     except SQLAlchemyError as db_error:
         await session.rollback()

surfsense_backend/app/tasks/connector_indexers/teams_indexer.py

@@ -460,7 +460,7 @@ async def index_teams_messages(
             documents_indexed,
             documents_skipped,
         )
-        return total_processed, result_message
+        return total_processed, None  # Return None on success (result_message is for logging only)
 
     except SQLAlchemyError as db_error:
         await session.rollback()

surfsense_backend/app/tasks/connector_indexers/webcrawler_indexer.py

@@ -400,7 +400,7 @@ async def index_crawled_urls(
             f"{documents_updated} updated, {documents_skipped} skipped, "
             f"{len(failed_urls)} failed"
         )
-        return total_processed, result_message
+        return total_processed, None  # Return None on success (result_message is for logging only)
 
     except SQLAlchemyError as db_error:
         await session.rollback()