src: do not pass nullptr to std::string ctor

nodejs/node#57354

Author: codebytere

patches/node/.patches

@@ -42,7 +42,6 @@ build_change_crdtp_protocoltypetraits_signatures_to_avoid_conflict.patch
 build_option_to_use_custom_inspector_protocol_path.patch
 fix_adjust_wpt_and_webidl_tests_for_enabled_float16array.patch
 chore_add_createexternalizabletwobytestring_to_globals.patch
-fix_-wnonnull_warning.patch
 refactor_attach_cppgc_heap_on_v8_isolate_creation.patch
 fix_ensure_traverseparent_bails_on_resource_path_exit.patch
 cli_move_--trace-atomics-wait_to_eol.patch