Fix missing assertions for native access functions

src/win32_window.c

@@ -32,6 +32,7 @@
 #include <limits.h>
 #include <stdlib.h>
 #include <string.h>
+#include <assert.h>
 #include <windowsx.h>
 #include <shellapi.h>
 
@@ -2577,6 +2578,8 @@ VkResult _glfwCreateWindowSurfaceWin32(VkInstance instance,
 GLFWAPI HWND glfwGetWin32Window(GLFWwindow* handle)
 {
     _GLFWwindow* window = (_GLFWwindow*) handle;
+    assert(window != NULL);
+
     _GLFW_REQUIRE_INIT_OR_RETURN(NULL);
 
     if (_glfw.platform.platformID != GLFW_PLATFORM_WIN32)