$i is 1
Array
(
    [0] => swap
    [1] => d7-d6
)
ILLEGAL: e4-d4;swap d7-d6 on turn 26:
The swap command does not have enough arguments.
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For diagnostic purposes, here is the full movelist:
1. P c2-c4; d5-d6 
1... e8-e6;swap e5 e6 
2. b1-c3; g6-f6 
2... c8-c6; swap c6 d6 
3. c3-d5;g4-g6 
3... b9-c7;b6-b3 
4. g2-g4;e6-e7 
4... g9-f7;swap f7 e7 
5. d5-e7;b3-b6 
5... f8-e7; swap c7 c6 
6. P b2-b3;c7-c8 
6... e7-e6; swap b8 c8 
7. f1-g2;b4-b7 
7... g8-g7; f7-f5 
8. g2-c6;b5-c5 
8... f9-c6;swap g6 g7 
9. h2-h4;c5-d5 
9... e9-g9;h9-f9; swap d6 d5 
10. c4-c5;f5-f7 
10... c8-c7;swap a8 b8 
11. g1-f3;b6-a6 
11... e5-e4;swap g6 f6 
12. f3-d4;g7-e7 
12... d8-d7;f7-g7 
13. d4-c6;g5-f5 
13... d7-c6;swap c6 d6 
14. c5-d6;g7-f7 
14... c7-d6;swap f6 f5 
15. g4-f5;a8-a7 
15... e6-f5; swap b8 b7 
16. a2-a4;c6-c7 
16... d9-d7;swap d7 c7 
17. h1-h3; f6-f8 
17... g9-h9;e7-g7 
18. h4-h5;g6-f6 
18... f9-e9;f6-f9 
19. h5-h6;f7-e7 
19... c9-d8; swap d8 d7 
20. B c1-b2; g7-g8 
20... f5-f4;e7-f7 
21. R a1-c1; swap a6 b6 
21... d7-c6; f7-f6 
22. B b2-d4; d8-d7 
22... e9-e7;swap c7 d7 
23. f2-f3; f6-e6 
23... a9-e9;e6-e5 
24. f3-e4;e5-f5 
24... e7-e4;f5-f6 
25. e2-e3; f6-e6 
25... f4-e3;swap e6 d6 
26. h3-e3;f8-f7 
26... e4-d4;swap d7-d6 
27. R c1-c6; swap c6 b6 
27... e6-e5; swap b7 c7 
28. Q d1-h5; swap b6 b7 
28... d7-g4; swap c6 c7 
29. Q h5-g4; swap b7 c7 
29... d4-g4;swap c6 d6 
30. R e3-h3; swap c7 c6 
30... e9-e6;b8-c8 
31. R c6-c3;a7-d7 
31... d5-d4;f7-g7 
32. R c3-g3; g7-g6 
32... g4-g3;g6-g5 
33. R h3-g3;b6-c6 
33... p d6-d5 
34. a4-a5; g5-g6 
34... e5-e4;c6-c5 
35. a5-a6;d7-d6 
35... d4-d3;swap d6 e6 
36. a6-a7;c5-c6 
36... d6-d9;c8-c5 
37. R g3-g5;c7-c4 
37... d9-a9;e6-e5 
|| 38. swap g6 h6 
|| 38... pass 
|| // Your last move was illegal as the rules state that : 'The
|| // stone move is optional, but the piece move is mandatory'. You
|| // have made a stone move but not a plain piece move :(!
38. g5-h5;swap g6 h6 
38... a9-a7;swap a7 b7 
39. b3-b4;c4-c7 
39... d5-d4;c7-c8 
40. b4-b5;c5-c7 
40... b7-b5;c8-d8 
41. g6-g7;swap h5 h6 
|| 41... h9-h8;swap h8 g8 
|| 42. h6-g6;h5-h6 
41... h9-g9;swap h8 g8 
42. h6-g6; h8-h7 
42... e4-e3;e5-e6 
43. P d2-e3;swap g7 h7 
43... d4-e3;swap f9 g9 
44. h7-g8;swap g7 g6 
44... b5-b1;swap g9 f9 
45. resign // - George Duke has resigned. -
In case there is a bug in the code, the settings file can be edited at /play/pbm/play.php?game=EIGHT-STONE+CHESS&settings=default&submit=Edit