core: add console error message if manager_startup() fails

src/core/main.c

@@ -2375,6 +2375,7 @@ int main(int argc, char *argv[]) {
         r = manager_startup(m, arg_serialization, fds);
         if (r < 0) {
                 log_error_errno(r, "Failed to fully start up daemon: %m");
+                error_message = "Failed to start up manager";
                 goto finish;
         }