If you steal something you don't know is toxic, and then eat it... how can you NOT deserve whatever outcome your actions have produced?
Not saying anyone deserves to be Killed for *A* fruit... but if someone intrudes someone's residence (or yard, in this case), and steals something, and then consumes that something, and that something happens to make them sick (and/or die), then that's what they get!
Plus, we're talking about a whole cannabis plant, not "A fruit." You didn't take the entire tree, did you?
If some ill fate befalls a thief, due to the very thing they stole... then good! I mean, it's unfortunate, but who else deserves to be blamed for whatever happens to the thief? He chose his actions, and gets whatever he gets.
Why couldn't he just take like a branch? Gotta take the WHOLE plant? If that dude comes back to steal more whole cannabis plants, i think maybe he DOES deserve to die for it. Although i'd always prefer the non-fatal option, since you can't suffer or feel remorse, if you're dead. I'd prefer to keep them alive to regret what they did.