Backends: Vulkan: non-dispatchable handles should compare to VK_NULL_HANDLE, not NULL (#4475)

backends/imgui_impl_vulkan.cpp

@@ -696,7 +696,7 @@ static void ImGui_ImplVulkan_CreateShaderModules(VkDevice device, const VkAlloca
 {
     // Create the shader modules
     ImGui_ImplVulkan_Data* bd = ImGui_ImplVulkan_GetBackendData();
-    if (bd->ShaderModuleVert == NULL)
+    if (bd->ShaderModuleVert == VK_NULL_HANDLE)
     {
         VkShaderModuleCreateInfo vert_info = {};
         vert_info.sType = VK_STRUCTURE_TYPE_SHADER_MODULE_CREATE_INFO;
@@ -705,7 +705,7 @@ static void ImGui_ImplVulkan_CreateShaderModules(VkDevice device, const VkAlloca
         VkResult err = vkCreateShaderModule(device, &vert_info, allocator, &bd->ShaderModuleVert);
         check_vk_result(err);
     }
-    if (bd->ShaderModuleFrag == NULL)
+    if (bd->ShaderModuleFrag == VK_NULL_HANDLE)
     {
         VkShaderModuleCreateInfo frag_info = {};
         frag_info.sType = VK_STRUCTURE_TYPE_SHADER_MODULE_CREATE_INFO;
@@ -1227,7 +1227,7 @@ void ImGui_ImplVulkanH_CreateWindowSwapChain(VkPhysicalDevice physical_device, V
 {
     VkResult err;
     VkSwapchainKHR old_swapchain = wd->Swapchain;
-    wd->Swapchain = NULL;
+    wd->Swapchain = VK_NULL_HANDLE;
     err = vkDeviceWaitIdle(device);
     check_vk_result(err);