OpenGL: Add an assert to catch a class of crash bugs early. Also assorted paranoia.

Common/GPU/OpenGL/GLRenderManager.h

@@ -532,6 +532,10 @@ public:
 		pushbuffer->End();
 	}
 
+	bool IsInRenderPass() const {
+		return curRenderStep_ && curRenderStep_->stepType == GLRStepType::RENDER;
+	}
+
 	// This starts a new step (like a "render pass" in Vulkan).
 	//
 	// After a "CopyFramebuffer" or the other functions that start "steps", you need to call this before

Common/GPU/Vulkan/thin3d_vulkan.cpp

@@ -1487,6 +1487,11 @@ void VKContext::DrawIndexed(int vertexCount, int offset) {
 }
 
 void VKContext::DrawUP(const void *vdata, int vertexCount) {
+	_dbg_assert_(vertexCount >= 0);
+	if (vertexCount <= 0) {
+		return;
+	}
+
 	VkBuffer vulkanVbuf, vulkanUBObuf;
 	size_t vbBindOffset = push_->Push(vdata, vertexCount * curPipeline_->stride[0], 4, &vulkanVbuf);
 	uint32_t ubo_offset = (uint32_t)curPipeline_->PushUBO(push_, vulkan_, &vulkanUBObuf);

GPU/GLES/DrawEngineGLES.cpp

@@ -250,6 +250,9 @@ void DrawEngineGLES::DoFlush() {
 	PROFILE_THIS_SCOPE("flush");
 	FrameData &frameData = frameData_[render_->GetCurFrame()];
 	
+	// Attempt to gather some information (asserts now upload the game name).
+	_assert_(render_->IsInRenderPass());
+
 	bool textureNeedsApply = false;
 	if (gstate_c.IsDirty(DIRTY_TEXTURE_IMAGE | DIRTY_TEXTURE_PARAMS) && !gstate.isModeClear() && gstate.isTextureMapEnabled()) {
 		textureCache_->SetTexture();

UI/MiscScreens.cpp

@@ -171,6 +171,7 @@ public:
 			int n = i & 3;
 			ui_draw2d.DrawImageRotated(symbols[n], x, y, 1.0f, angle, colorAlpha(colors[n], alpha * 0.1f));
 		}
+		dc.Flush();
 	}
 
 private: