unbind VAO if NULL buffer specified

libobs-opengl/gl-vertexbuffer.c

@@ -260,8 +260,10 @@ bool vertexbuffer_load(device_t device, vertbuffer_t vb)
 		return true;
 
 	device->cur_vertex_buffer = vb;
-	if (!device->cur_vertex_shader || !vb)
+	if (!device->cur_vertex_shader || !vb) {
+		gl_bind_vertex_array(0);
 		return true;
+	}
 
 	if (!load_vb_buffers(device->cur_vertex_shader, vb))
 		return false;