diff -r 30476eaff3ba -r 6ebe1b98f53b ui/winui/toolkit.cpp
--- a/ui/winui/toolkit.cpp	Thu May 28 21:17:26 2026 +0200
+++ b/ui/winui/toolkit.cpp	Thu May 28 21:18:33 2026 +0200
@@ -149,6 +149,9 @@
 	}
 }
 
+// NOOP on most platforms, expect macos
+UIEXPORT extern "C" 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;