Fixes issue where failed start of OpenXR causes issues

modules/openxr/openxr_api.cpp

@@ -560,6 +560,12 @@ void OpenXRAPI::destroy_instance() {
 		instance = XR_NULL_HANDLE;
 	}
 	enabled_extensions.clear();
+
+	if (graphics_extension != nullptr) {
+		unregister_extension_wrapper(graphics_extension);
+		memdelete(graphics_extension);
+		graphics_extension = nullptr;
+	}
 }
 
 bool OpenXRAPI::create_session() {
@@ -1347,6 +1353,10 @@ void OpenXRAPI::register_extension_wrapper(OpenXRExtensionWrapper *p_extension_w
 	registered_extension_wrappers.push_back(p_extension_wrapper);
 }
 
+void OpenXRAPI::unregister_extension_wrapper(OpenXRExtensionWrapper *p_extension_wrapper) {
+	registered_extension_wrappers.erase(p_extension_wrapper);
+}
+
 void OpenXRAPI::register_extension_metadata() {
 	for (OpenXRExtensionWrapper *extension_wrapper : registered_extension_wrappers) {
 		extension_wrapper->on_register_metadata();

modules/openxr/openxr_api.h

@@ -312,6 +312,7 @@ public:
 
 	void set_xr_interface(OpenXRInterface *p_xr_interface);
 	static void register_extension_wrapper(OpenXRExtensionWrapper *p_extension_wrapper);
+	static void unregister_extension_wrapper(OpenXRExtensionWrapper *p_extension_wrapper);
 	static void register_extension_metadata();
 	static void cleanup_extension_wrappers();
 

modules/openxr/register_types.cpp

@@ -111,6 +111,10 @@ void initialize_openxr_module(ModuleInitializationLevel p_level) {
 			ERR_FAIL_NULL(openxr_api);
 
 			if (!openxr_api->initialize(Main::get_rendering_driver_name())) {
+				OS::get_singleton()->alert("OpenXR was requested but failed to start.\n"
+										   "Please check if your HMD is connected.\n"
+										   "When using Windows MR please note that WMR only has DirectX support, make sure SteamVR is your default OpenXR runtime.\n"
+										   "Godot will start in normal mode.\n");
 				memdelete(openxr_api);
 				openxr_api = nullptr;
 				return;