Handle missing tables in datatables responses

[Ulthran]

Motivation

• Prevent 500 errors from DataTables endpoints when underlying tables or queries are missing or invalid by returning a consistent empty DataTables response.
• Ensure both raw SQL and SQLAlchemy Select code paths behave consistently when the database cannot execute the query.

Description

• Add imports for OperationalError and ProgrammingError from sqlalchemy.exc and create an empty_response helper to return an empty DataTables-shaped response.
• Wrap raw SQL path column discovery and counting/pagination logic in try/except blocks that return empty_response on OperationalError/ProgrammingError.
• Wrap the SQLAlchemy Select path (counts, filtering, ordering, pagination) in a try/except block that returns empty_response on database errors.
• Move retrieval of request.values to the function start so it can be reused and ensure response draw/columns remain consistent.

Testing

• Ran code formatting with black . which completed successfully.
• Ran pytest tests/ and all tests passed: 9 passed.

---

Codex Task

[Copilot]

Pull request overview

This PR adds error handling to the datatables_response function to prevent 500 errors when database queries fail due to missing tables or invalid SQL. Instead of crashing, the function now returns an empty DataTables-formatted response.

Changes:

• Added database exception imports (OperationalError, ProgrammingError) and an empty_response helper function
• Wrapped raw SQL path operations (column discovery and query execution) in try/except blocks
• Wrapped SQLAlchemy Select path operations in a try/except block
• Moved request.values retrieval to function start for consistency

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

The lines that access query.selected_columns (lines 140-141) are executed before the try/except block begins at line 142. If the query references a non-existent table or has other structural issues, accessing selected_columns or calling with_only_columns() could raise an OperationalError or ProgrammingError before error handling is active. Move lines 140-141 inside the try block to ensure all operations that could fail due to database issues are protected.