Feathers_McGraw's Hammerhead Torch from the openrepos works. One in Jolla Store doesn't as it hasn't been updated lately. The difference between versions is that the latest defaults to Gstreamer to control the led. Personally I like to use app since you can add the flashlight app to the lockscreen as a shortcut. (I also find it ugly and confusing how SailfishOS has quick controls behind only one of the screens in the carousel, and not both, so I keep those disabled.)