Marlin 336 lever has a cross bolt safety that when on will not let the gun fire. It was put there for when the user is unloading and has to cycle all the rounds thru the action in order to get them out. I don't have a problem with this safety feature and use it when unloading. I immediately turn it back off after because its easy to forget about and I don't want to be on a buck and hear click when I pull the trigger.
This cross block safety would also prevent the rifle from accidental discharge if the hammer slipped when de-cocking. I have never had a concern de-cocking a lever gun but some pistols are a little tricky.