Top down sleeves

I am knitting a top down raglan sleeve sweater the Venlig pullover. The pattern does not call for casting stitches on for sleeve underarm is this common I will have small hole do I just close it

There are at least a couple of ways to avoid a hole. You can either knit the 1- 2sts in the middle of the underarm through the back loop to tighten them up or you could pick up a stitch or two at the underarm then on the next round, knit them together with the stitches on either side.