### Godot version

4.0 Beta 11

### System information

Windows 10 version 22H2, GeForce Game Ready Driver Version 528.02, GTX 1070

### Issue description

Since Beta 11 this error is given whenever a project is run in the forward+ renderer with OpenXR enabled. This error is not present with Beta 10 and previous versions.
![image](https://user-images.githubusercontent.com/38119387/212044209-1179b908-f010-47a1-ae53-bc2faadc30de.png)

I've tested with projects created in previous versions as well as the current version (Beta 11)

### Steps to reproduce

Create project, enable OpenXR in project settings, and run.

### Minimal reproduction project

N/A
ERR_FAIL_COND_V_MSG(instance != XR_NULL_HANDLE, false, "OpenXR instance was already created");
	if (!openxr_loader_init()) {
		return false;
	}
	if (p_rendering_driver == "vulkan") {
#ifdef VULKAN_ENABLED
		graphics_extension = memnew(OpenXRVulkanExtension);
		register_extension_wrapper(graphics_extension);
#else
		
		ERR_FAIL_V(false);
#endif
	} else if (p_rendering_driver == "opengl3") {
#ifdef GLES3_ENABLED
		graphics_extension = memnew(OpenXROpenGLExtension);
		register_extension_wrapper(graphics_extension);
#else
		
		ERR_FAIL_V(false);
#endif
	} else {
		ERR_FAIL_V_MSG(false, "OpenXR: Unsupported rendering device.");
	}
	
	for (OpenXRExtensionWrapper *wrapper : registered_extension_wrappers) {
		wrapper->on_before_instance_created();
	}
	if (!load_layer_properties()) {