Store source metadata for imported documents (#6136)

server/errors.ts

@@ -87,6 +87,12 @@ export function InvalidRequestError(message = "Request invalid") {
   });
 }
 
+export function PaymentRequiredError(message = "Payment required") {
+  return httpErrors(402, message, {
+    id: "payment_required",
+  });
+}
+
 export function NotFoundError(message = "Resource not found") {
   return httpErrors(404, message, {
     id: "not_found",