Funcom is aware of the issue as you’ll see in my next link.
There seem to be some safe ways for your followers in the volcano.
i have been farming this spot for several days and this is the only bridge where my follower and palm’s follower died : Thrall on follow keep dying in the volcano
All other bridges seem to be safe, as long as you walk straight in the midlle of them and you wait for your follower to be standing right before the bridge before crossing it ( this might have Nothing to do with it though…but this is how i do it now)
Other than that try to avoid wandering to close from the lava and climbing in this area.