I'm working through the tutorial and I found that when I got to the end of 01-hello-world, I was encountering the following error:
$ go run traffic.go
# engo.io/engo/common
../../../engo.io/engo/common/animation.go:99:11: invalid map key type ecs.BasicEntity
../../../engo.io/engo/common/animation.go:110:21: invalid map key type ecs.BasicEntity
$ cd /src/engo.io/ecs/
$ git checkout v1.0
(Apologies for not raising a PR to fix the doc but I wasn't sure about the best place to put a note about this. In the foreword?)