Improve unregistering XR interfaces so we don't get crashes in GDExtensions by destroying the XRServer too early

main/main.cpp

@@ -2689,8 +2689,9 @@ void Main::cleanup(bool p_force) {
 	rendering_server->global_variables_clear();
 
 	if (xr_server) {
-		// cleanup now before we pull the rug from underneath...
+		// Now that we're unregistering properly in plugins we need to keep access to xr_server for a little longer
-		memdelete(xr_server);
+		// We do however unset our primary interface
+		xr_server->set_primary_interface(Ref<XRInterface>());
 	}
 
 	unregister_driver_types();
@@ -2706,6 +2707,10 @@ void Main::cleanup(bool p_force) {
 	unregister_scene_types();
 	unregister_server_types();
 
+	if (xr_server) {
+		memdelete(xr_server);
+	}
+
 	if (audio_server) {
 		audio_server->finish();
 		memdelete(audio_server);

modules/mobile_vr/register_types.cpp

@@ -32,15 +32,30 @@
 
 #include "mobile_vr_interface.h"
 
+Ref<MobileVRInterface> mobile_vr;
+
 void register_mobile_vr_types() {
 	GDREGISTER_CLASS(MobileVRInterface);
 
 	if (XRServer::get_singleton()) {
-		Ref<MobileVRInterface> mobile_vr;
 		mobile_vr.instantiate();
 		XRServer::get_singleton()->add_interface(mobile_vr);
 	}
 }
 
 void unregister_mobile_vr_types() {
+	if (mobile_vr.is_valid()) {
+		// uninitialise our interface if it is initialised
+		if (mobile_vr->is_initialized()) {
+			mobile_vr->uninitialize();
+		}
+
+		// unregister our interface from the XR server
+		if (XRServer::get_singleton()) {
+			XRServer::get_singleton()->remove_interface(mobile_vr);
+		}
+
+		// and release
+		mobile_vr.unref();
+	}
 }

modules/webxr/register_types.cpp

@@ -33,15 +33,34 @@
 #include "webxr_interface.h"
 #include "webxr_interface_js.h"
 
+#ifdef JAVASCRIPT_ENABLED
+Ref<WebXRInterfaceJS> webxr;
+#endif
+
 void register_webxr_types() {
 	GDREGISTER_VIRTUAL_CLASS(WebXRInterface);
 
 #ifdef JAVASCRIPT_ENABLED
-	Ref<WebXRInterfaceJS> webxr;
 	webxr.instantiate();
 	XRServer::get_singleton()->add_interface(webxr);
 #endif
 }
 
 void unregister_webxr_types() {
+#ifdef JAVASCRIPT_ENABLED
+	if (webxr.is_valid()) {
+		// uninitialise our interface if it is initialised
+		if (webxr->is_initialized()) {
+			webxr->uninitialize();
+		}
+
+		// unregister our interface from the XR server
+		if (XRServer::get_singleton()) {
+			XRServer::get_singleton()->remove_interface(webxr);
+		}
+
+		// and release
+		webxr.unref();
+	}
+#endif
 }