In attempting to create a short program to approximate a fibonacci spiral, I created the following function to draw a 90-degree arc with a given radius, and called it within a while loop. The following full program works fine:

$max = 300
$a = 0
$b = 1
$t = 0

learn arc $rad {
  $d = round((pi * $rad) / 2)
  for $i = 1 to $d {
    forward 1
    turnleft 90 / $rad
  }
}

reset
while $b < $max {
  arc $b

  $t = $b
  $b = $a + $b
  $a = $t
}

However, in order to verify the spiral, I wanted to add the boxes you often see around them, by adding four "forward" commands:

$max = 300
$a = 0
$b = 1
$t = 0

learn arc $rad {
  $d = round((pi * $rad) / 2)
  for $i = 1 to $d {
    forward 1
    turnleft 90 / $rad
  }
}

reset
while $b < $max {
  forward $b
  turnleft 90
  forward $b
  turnleft 90
  forward $b
  turnleft 90
  forward $b
  turnleft 90

  arc $b

  $t = $b
  $b = $a + $b
  $a = $t
}

This crashes the program. Oddly enough, it even crashes when I then comment out the "arc" call. However, moving the contents of the function in-line works fine:

$max = 300
$a = 0
$b = 1
$t = 0

reset
while $b < $max {
  forward $b
  turnleft 90
  forward $b
  turnleft 90
  forward $b
  turnleft 90
  forward $b
  turnleft 90

  $d = round((pi * $b) / 2)
  for $i = 1 to $d {
    forward 1
    turnleft 90 / $b
  }

  $t = $b
  $b = $a + $b
  $a = $t
}

Reproducible: Always

Steps to Reproduce:
1.  Input the above code into the editor
2.  Hit "run"
3.  Observe as the program crashes
Actual Results:  
The program just dies, running it from a tty simply gives me:
» kturtle
kturtle(1332)/kdeui (kdelibs): Attempt to use QAction "" with KXMLGUIFactory! 
"/org/freedesktop/UDisks2/drives/WDC_WD7501AALS_00E3A0_WD_WCATR1687391" : property "Drive" does not exist 
"/org/freedesktop/UDisks2/drives/Optiarc_DVD_RW_AD_7260S_Optiarc_DVD_RW_AD_7260S" : property "Drive" does not exist 
"/org/freedesktop/UDisks2/drives/Floppy_Drive" : property "Drive" does not exist 
"/org/freedesktop/UDisks2/drives/USB_2_2e0_USB_Flash_Drive_AA00000000000108" : property "Drive" does not exist 
"/org/freedesktop/UDisks2/block_devices/fd0" : property "Name" does not exist 
"/org/freedesktop/UDisks2/drives/Floppy_Drive" : property "DeviceNumber" does not exist 
"/org/freedesktop/UDisks2/drives/Floppy_Drive" : property "Device" does not exist 
"/org/freedesktop/UDisks2/drives/USB_2_2e0_USB_Flash_Drive_AA00000000000108" : property "DeviceNumber" does not exist 
"/org/freedesktop/UDisks2/drives/USB_2_2e0_USB_Flash_Drive_AA00000000000108" : property "Device" does not exist 
"/org/freedesktop/UDisks2/drives/WDC_WD7501AALS_00E3A0_WD_WCATR1687391" : property "DeviceNumber" does not exist 
"/org/freedesktop/UDisks2/drives/WDC_WD7501AALS_00E3A0_WD_WCATR1687391" : property "Device" does not exist 
KCrash: Application 'kturtle' crashing...
KCrash: Attempting to start /usr/lib/kde4/libexec/drkonqi from kdeinit
sock_file=/home/dj/.kde4/socket-medinvdj/kdeinit4__0


Expected Results:  
The program should have drawn the exact same thing as the final example above.

I'm going to play around with it and see if I can whittle stuff away to get to the bare minimum needed to reproduce. I haven't used this bug tracker before, hopefully I'll be able to comment with updates.

Thanks for your time