When executing the following code:

//
// Drawing a conic section using the polar equation
//
void setup()
{
 size(1200, 800);
 background(255);  
 noLoop();
}

void draw()
{
 line(width / 2, 0, width / 2, height);
 line(0, height / 2, width, height / 2);
 translate(width / 2, height / 2);
 
 float p = 150;
 float e = 1.0;
 
 for (int i = 0; i < 10; i++)
 {
   conicSection(p, e, 5000);
   //directrix(p, e);
   e = e - 0.1;
 }
}
 
void conicSection(float p, float e, int numberOfPoints)
{
 float theta = 0;
 stroke(100);
 smooth();
 line(-width / 2, p, width / 2, p);
 line(-width / 2, -p, width / 2, -p);

 stroke(0);

 strokeWeight(2);
 for (int i = 0; i < numberOfPoints; i++)
 {    
   float r = p / (1 - e * cos(theta));
   float x = r * cos(theta);
   float y = r * sin(theta);
   point(x, y);
   theta = theta + TWO_PI / numberOfPoints;
 } // end for
} // end conicSection

void directrix(float p, float e)
{
 line(-p / e, -height / 2, -p / e, width / 2);
}

I get the following stack trace in the text area:

sun.dc.pr.PRException: endPath: bad path


at sun.dc.pr.Rasterizer.endPath(Unknown Source)


at sun.java2d.pipe.DuctusRenderer.createShapeRasterizer(Unknown Source)


at sun.java2d.pipe.DuctusShapeRenderer.renderPath(Unknown Source)


at sun.java2d.pipe.DuctusShapeRenderer.draw(Unknown Source)


at sun.java2d.SunGraphics2D.draw(Unknown Source)


at processing.core.PGraphicsJava2D.stroke_shape(PGraphicsJava2D.java:484)


at processing.core.PGraphicsJava2D.line(PGraphicsJava2D.java:518)


at processing.core.PGraphicsJava2D.point(PGraphicsJava2D.java:510)


at processing.core.PApplet.point(PApplet.java:7404)


at Temporary_6791_8151.conicSection(Temporary_6791_8151.java:44)


at Temporary_6791_8151.draw(Temporary_6791_8151.java:22)


at processing.core.PApplet.handleDisplay(PApplet.java:1465)


at processing.core.PGraphics.requestDisplay(PGraphics.java:690)


at processing.core.PApplet.run(PApplet.java:1562)


at java.lang.Thread.run(Unknown Source)