Logging trpc errors in production

const createContext = async (req: NextRequest) => {
  return createTRPCContext({
    headers: req.headers,
  });
};

const handler = (req: NextRequest) =>
  fetchRequestHandler({
    endpoint: '/api/trpc',
    req,
    router: appRouter,
    createContext: () => createContext(req),
    onError: ({ path, error }) => {
      if (serverEnv.NODE_ENV === 'development') {
        trpcLogger.error(
          `❌ tRPC failed on ${path ?? '<no-path>'}: ${error.message}`,
        );
      }
    },
  });

export { handler as GET, handler as POST };

export const api = createTRPCProxyClient<AppRouter>({
  transformer,
  links: [
    loggerLink({
      enabled: (op) =>
        process.env.NODE_ENV === 'development' ||
        (op.direction === 'down' && op.result instanceof Error),
    }),
    /**
     * Custom RSC link that lets us invoke procedures without using http requests. Since Server
     * Components always run on the server, we can just call the procedure as a function.
     */
    () =>
      ({ op }) =>
        observable((observer) => {
          createContext()
            .then((ctx) => {
              return callProcedure({
                procedures: appRouter._def.procedures,
                path: op.path,
                rawInput: op.input,
                ctx,
                type: op.type,
              });
            })
            .then((data) => {
              observer.next({ result: { data } });
              observer.complete();
            })
            .catch((cause: TRPCErrorResponse) => {
              observer.error(TRPCClientError.from(cause));
            });
        }),
  ],
});