Castling bug

[strikegol]

I am seeing e1h1 instead of e1g1 for kingside castling. Is this not a bug?

FEN: r1bqk1nr/pppp1ppp/2n5/2b1p3/2B1P3/5N2/PPPP1PPP/RNBQK2R w KQkq - 0 1
8 r.bqk.nr
7 pppp.ppp
6 ..n.....
5 ..b.p...
4 ..B.P...
3 .....N..
2 PPPP.PPP
1 RNBQK..R
abcdefgh

Legal Moves (Raw Data):
Move: a2a3, FromSquare: a2, ToSquare: a3, MoveType: Normal
Move: b2b3, FromSquare: b2, ToSquare: b3, MoveType: Normal
Move: c2c3, FromSquare: c2, ToSquare: c3, MoveType: Normal
Move: d2d3, FromSquare: d2, ToSquare: d3, MoveType: Normal
Move: g2g3, FromSquare: g2, ToSquare: g3, MoveType: Normal
Move: h2h3, FromSquare: h2, ToSquare: h3, MoveType: Normal
Move: a2a4, FromSquare: a2, ToSquare: a4, MoveType: Normal
Move: b2b4, FromSquare: b2, ToSquare: b4, MoveType: Normal
Move: d2d4, FromSquare: d2, ToSquare: d4, MoveType: Normal
Move: g2g4, FromSquare: g2, ToSquare: g4, MoveType: Normal
Move: h2h4, FromSquare: h2, ToSquare: h4, MoveType: Normal
Move: f3g1, FromSquare: f3, ToSquare: g1, MoveType: Normal
Move: f3d4, FromSquare: f3, ToSquare: d4, MoveType: Normal
Move: f3h4, FromSquare: f3, ToSquare: h4, MoveType: Normal
Move: f3e5, FromSquare: f3, ToSquare: e5, MoveType: Normal
Move: f3g5, FromSquare: f3, ToSquare: g5, MoveType: Normal
Move: b1a3, FromSquare: b1, ToSquare: a3, MoveType: Normal
Move: b1c3, FromSquare: b1, ToSquare: c3, MoveType: Normal
Move: c4f1, FromSquare: c4, ToSquare: f1, MoveType: Normal
Move: c4e2, FromSquare: c4, ToSquare: e2, MoveType: Normal
Move: c4b3, FromSquare: c4, ToSquare: b3, MoveType: Normal
Move: c4d3, FromSquare: c4, ToSquare: d3, MoveType: Normal
Move: c4b5, FromSquare: c4, ToSquare: b5, MoveType: Normal
Move: c4d5, FromSquare: c4, ToSquare: d5, MoveType: Normal
Move: c4a6, FromSquare: c4, ToSquare: a6, MoveType: Normal
Move: c4e6, FromSquare: c4, ToSquare: e6, MoveType: Normal
Move: c4f7, FromSquare: c4, ToSquare: f7, MoveType: Normal
Move: h1f1, FromSquare: h1, ToSquare: f1, MoveType: Normal
Move: h1g1, FromSquare: h1, ToSquare: g1, MoveType: Normal
Move: d1e2, FromSquare: d1, ToSquare: e2, MoveType: Normal
Move: e1f1, FromSquare: e1, ToSquare: f1, MoveType: Normal
Move: e1e2, FromSquare: e1, ToSquare: e2, MoveType: Normal
Move: e1h1, FromSquare: e1, ToSquare: h1, MoveType: Castling

Legal Moves (Algebraic Notation):
a2a3
b2b3
c2c3
d2d3
g2g3
h2h3
a2a4
b2b4
d2d4
g2g4
h2h4
f3g1
f3d4
f3h4
f3e5
f3g5
b1a3
b1c3
c4f1
c4e2
c4b3
c4d3
c4b5
c4d5
c4a6
c4e6
c4f7
h1f1
h1g1
d1e2
e1f1
e1e2
e1h1