Errata as follows:

For right legwarmer:

Begin Cable Panel
Row 1 (RS): Change to Size 6 ndls, with MC K42; join CC and holding tog with MC, K9; K11 with MC only.
Row 2 (WS): P11; pick up CC and hold tog with MC, P9; P42 with MC only.
Rows 3-4: Rep these 2 rows, once more.
Row 5 (RS): K42; slip 3 sts to cable needle (cn) and hold in front of work, with MC and CC held tog K3, K3 from cn, K3; K11 with MC only.
Row 6: Work as for Row 2.
Rows 7-10: Rep Rows 1 & 2, twice.
Row 11: K42; with MC and CC held tog K3, sl 3 sts to cn and hold at back of work, K3, K3 from cn; K11 with MC only.
Row 12: Work as for Row 2.
Rep Rows 1-12, 7 more times.

For left legwarmer:
Begin Cable Panel
Row 1 (RS): Change to Size 6 ndls, with MC K11; join CC and holding tog with MC, K9; K42 with MC only.
Row 2 (WS): P42; pick up CC and hold tog with MC, P9; P11 with MC only.
Rows 3-4: Rep these 2 rows, once more.
Row 5 (RS): K11; with MC and CC held tog K3, sl 3 sts to cn and hold at back of work, K3, K3 from cn; K42 with MC only.
Row 6: Work as for Row 2.
Rows 7-10: Rep Rows 1 & 2, twice.
Row 11: K11; slip 3 sts to cable needle and hold in front of work, with MC and CC held tog K3, K3 from cn, K3; K42 with MC only.
Row 12: Work as for Row 2.
Rep Rows 1-12, 7 more times.