add check for starting a frame in an invalid situation

vulkan.d

@@ -439,6 +439,11 @@ struct Vulkan
   Arena                          arena;
   Arena[FRAME_OVERLAP]           frame_arenas;
 
+	debug
+	{
+		bool frame_started;
+	}
+
   u32                            frame_index;
   u32                            semaphore_index;
 
@@ -774,6 +779,16 @@ MapBuffer(T)(Buffer* buffer, u64 count)
 void
 BeginFrame()
 {
+	debug
+	{
+		if(g_vk.frame_started)
+		{
+			assert(false, "BeginFrame called twice, did you forget to end the frame?");
+		}
+
+		g_vk.frame_started = true;
+	}
+
   // TODO: move vkWaitForFences so it no longer holds up the frame, will need to change how fences are handled in regards to images though
   VkResult result = vkWaitForFences(g_vk.device, 1, g_vk.render_fence_ptr, VK_TRUE, 1000000000);
   VkCheckA("BeginFrame failure: vkWaitForFences error", result);
@@ -961,6 +976,11 @@ SubmitAndPresent()
   {
     VkCheckA("FinishFrame failure: vkQueuePresentKHR failure", result);
   }
+
+	debug
+	{
+		g_vk.frame_started = false;
+	}
 }
 
 void