Bug: lookupByUAL returns OK on internal errors, masking failures

[Bojan131]

Description

In packages/query/src/query-handler.ts, the lookupByUAL method catches all errors and returns a success response (OK) with empty data, effectively masking database failures and other internal errors.

Impact

• High severity — If the Oxigraph storage is down or a query fails, the caller receives a "success" response with no data instead of an error. This makes it impossible to distinguish between "no data exists" and "the database is broken".
• Debugging production issues becomes extremely difficult because errors are silently swallowed.
• Clients may incorrectly assume a UAL doesn't exist when the underlying storage is actually failing.

Code Pattern

The problematic pattern (approximate):

async lookupByUAL(ual: string) {
  try {
    // ... query storage ...
    return { status: 'OK', data: results };
  } catch (err) {
    // BUG: Returns success with empty data instead of propagating the error
    return { status: 'OK', data: [] };
  }
}

Suggested Fix

The catch block should return an error status:

catch (err) {
  log.error('lookupByUAL failed:', err);
  return { status: 'ERROR', error: err.message };
}

Location

packages/query/src/query-handler.ts — lookupByUAL method.