--- a/ui/win32/toolkit.c	Thu May 28 17:45:20 2026 +0200
+++ b/ui/win32/toolkit.c	Thu May 28 18:07:00 2026 +0200
@@ -49,6 +49,9 @@
 
 static HFONT ui_font = NULL;
 
+// NOOP on most platforms, expect macos
+UIEXPORT void ui_set_main_thread_error_msg(const char *msg) {}
+
 void ui_init(const char *appname, int argc, char **argv) {
     application_name = appname ? strdup(appname) : NULL;