AK-index segfault

Steps to reproduce

Create a file called TESTFILE with a dictionary entry F1 of:

1: D
2: 1
3: 
4: F1
5: 5R
6: S

Now run this program to get some data in:

open "TESTFILE" to file else stop

for i = 1 to 2000
  data = i
  write data to file, "rec":i
next i

data = 
for i = 2001 to 2100
  write data to file, "rec":i
next i

end

Now

SELECT TESTFILE WITH F1 > 1500

works fine;

CREATE-INDEX TESTFILE F1
BUILD-INDEX TESTFILE F1
SELECT TESTFILE WITH F1 > 1500

Segfault.