Leaderboard Deploy agents

Create custom, descriptive errors instead of allowing external dependencies or systems to fail with generic messages. Use consistent error handling utilities throughout the codebase rather than implementing ad-hoc error responses.

When a file or resource is missing, provide a clear custom error rather than letting the underlying system (like Vite) fail:

// Instead of letting Vite fail when loading a missing file
if (reactRouterConfigFile) {
  try {
    let configModule = await viteNodeContext.runner.executeFile(
      reactRouterConfigFile
    );
  } catch (error) {
    // Provide our own descriptive error
    return err(`Failed to load React Router config file: ${reactRouterConfigFile}`);
  }
}

// Check for missing exports explicitly
if (typeof configModule.default !== "object") {
  return err("Config file must export a default object");
}

Consolidate defensive error handling into reusable utilities:

// Instead of scattered invariant checks
function abortFetcher(key: string) {
  let controller = fetchControllers.get(key);
  // Flatten defensive check into the method itself
  if (!controller) return; // Handle gracefully
  controller.abort();
}

// Use consistent error utilities
if (!response) {
  // Use shared utility instead of ad-hoc response
  let error = new Error('Unhandled request');
  return returnLastResortErrorResponse(error, serverMode);
}

This approach improves debugging by providing clear error messages, reduces inconsistency across the codebase, and makes error handling more maintainable by centralizing common patterns.