message: Check that drawSwapChain exists inside endFrame
diff: @@ -160,7 +160,9 @@ void MetalDriver::endFrame(uint32_t frameId) {
  mContext->bufferPool->gc();
  // If we acquired a drawable for this frame, ensure that we release it here.
  + if (mContext->currentDrawSwapChain) {
  mContext->currentDrawSwapChain->releaseDrawable();
  + }
  CVMetalTextureCacheFlush(mContext->textureCache, 0);
  