Drawing a PGraphics while saving a PDF crashes

Processing
1

This might be more of a curiosity than a “bug” I want to solve. My main motivation was to draw shapes and have them clipped by the PGraphics canvas before applying them elsewhere.

When drawing the Pgraphics with image() it normaly works fine, but when recording a PDF frame I get this:

ClassCastException: class sun.java2d.SunGraphics2D cannot be cast to class java.awt.Image (sun.java2d.SunGraphics2D and java.awt.Image are in module java.desktop of loader 'bootstrap')

… when running the code below…

import processing.pdf.*;

boolean savePDF = false;
PFont f;
PGraphics pg;

void setup() {
  size(400, 400);
  textMode(SHAPE);
  f = createFont("DejaVu Sans", 100);
  pg = createGraphics(300, 300);
  pg.beginDraw();
  pg.background(0, 100, 0);
  pg.textAlign(CENTER, CENTER);
  pg.textFont(f);
  pg.textSize(pg.width / 8);
  pg.textMode(SHAPE);
  pg.text("hello", pg.width * 0.6, pg.height * 0.6);
  pg.endDraw();
}

void draw() {
  if (savePDF) {
    PGraphics pdf = createGraphics(width, height, PDF, "out.pdf");
    beginRecord(pdf);
  }
  imageMode(CENTER);
  int x = 200;
  int y = 200;
  float rot = PI / 4;
  pushMatrix();
  translate(x, y);
  rotate(rot);
  image(pg, 0, 0);
  popMatrix();
  if (savePDF) {
    endRecord();
    savePDF = false;
  }

}
void keyPressed() {
  savePDF = true;
}

It works if I use pg.copy() that gets me a PImage object, but maybe I don’t want to do that because I don’t want a raster of the vector-graphics…