--- a/ui/gtk/toolkit.c	Thu May 28 21:17:26 2026 +0200
+++ b/ui/gtk/toolkit.c	Thu May 28 21:18:33 2026 +0200
@@ -62,6 +62,9 @@
 
 static UiBool        exit_on_shutdown;
 
+// NOOP on most platforms, expect macos
+void ui_set_main_thread_error_msg(const char *msg) {}
+
 UIEXPORT void ui_init(const char *appname, int argc, char **argv) {
     application_name = appname ? strdup(appname) : NULL;
     uic_init_global_context();