fixes comments panic when using move history from Move()

game.go

@@ -164,6 +164,7 @@ func (g *Game) Move(m *Move) error {
 	g.moves = append(g.moves, valid)
 	g.pos = g.pos.Update(valid)
 	g.positions = append(g.positions, g.pos)
+	g.comments = append(g.comments, []string{})
 	g.updatePosition()
 	return nil
 }

game_test.go

@@ -280,6 +280,17 @@ func TestMoveHistory(t *testing.T) {
 	}
 }
 
+func TestMoveHistoryProgrammatic(t *testing.T) {
+	game := NewGame()
+	game.MoveStr("e4")
+	game.MoveStr("e5")
+	game.Resign(Black)
+	history := game.MoveHistory() // Panics here
+	if len(history) != 2 {
+		t.Fatal("Didn't retrieve full history")
+	}
+}
+
 func BenchmarkStalemateStatus(b *testing.B) {
 	fenStr := "k1K5/8/8/8/8/8/8/1Q6 w - - 0 1"
 	fen, err := FEN(fenStr)

pgn.go

@@ -180,6 +180,7 @@ func decodePGN(pgn string) (*Game, error) {
 		if err := g.Move(m); err != nil {
 			return nil, fmt.Errorf("chess: pgn invalid move error %s on move %d", err.Error(), g.Position().moveCount)
 		}
+		g.comments = g.comments[:len(g.comments)-1]
 		g.comments = append(g.comments, move.Comments)
 	}
 	g.outcome = outcome