message: If readPixels() returns early it must pop the stack first...
diff: @@ -654,8 +654,10 @@ export abstract class Target extends RenderTarget {
  this._renderCommands.clearCheckRange();
  // Don't bother rendering + reading if we know there's nothing to draw.
  - if (this._renderCommands.isEmpty)
  + if (this._renderCommands.isEmpty) {
  + this._stack.pop(); // ensure state is restored!
  return undefined;
  + }
  // Draw the scene
  this.compositor.drawForReadPixels(this._renderCommands);
  