Fix missing assertions for native access functions

src/wl_window.c

@@ -3298,6 +3298,8 @@ GLFWAPI struct wl_display* glfwGetWaylandDisplay(void)
 GLFWAPI struct wl_surface* glfwGetWaylandWindow(GLFWwindow* handle)
 {
     _GLFWwindow* window = (_GLFWwindow*) handle;
+    assert(window != NULL);
+
     _GLFW_REQUIRE_INIT_OR_RETURN(NULL);
 
     if (_glfw.platform.platformID != GLFW_PLATFORM_WAYLAND)