Errata and notes on the paper "A generalization of Springer theory using nearby cycles"

We provide some corrections and clarifications to the paper [Gr3] of the title. In particular, we clarify the “left/right” conventions on complex reflection groups and their braid groups. Most importantly, we fill in a gap related to the treatment of cuts in the Picard-Lefschetz theory part of the argument. The statements of the main results are not affected.