Distribution from createProjection has erroneus plot

[Wile_E_Coyote]

To me, it looks like a usual/known ROOT integrator’s misbehaviour.

{
  RooRealVar x("x", "x", 1, 3);
  RooRealVar lambda("lambda", "rate", 1, 0, 100);
  RooGenericPdf expo("expo", "expo",
                     "lambda * exp(-lambda * x)",
                     RooArgList(x, lambda));
  auto marginal_x = expo.createProjection(RooArgSet(lambda));
  RooPlot *xFrame = x.frame();
  marginal_x->plotOn(xFrame);
  xFrame->Draw();
}