Do you think an armed robber should spend the rest of their life in prison?

It would have to be concealed to not be considered armed robbery. Then it would be considered simple robbery. As I've said a dozen times before, robbery means threatening somebody in order to get their money/goods. If there is no threat, it's not robbery, but theft. If the gun was openly carried or in the hand, it would be armed robbery. Brandishing a weapon in the commission of a crime is the same as threatening somebody with it. In the process of committing a felony, a criminal has no right to self defense.

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Nope, if I shoot my friend accidentally while in process of trying to kill the criminal, the felony murder law puts it on the criminal. The reason I shot my gun was due to his actions. The criminal is responsible.

 

I started a new thread specifically on this subject: Holding a criminal responsible for the indirect results of their crime

Take the argument there.

 

I'd rather keep it here.

 

Why? A robber has no right to defend himself while committing his crime. The two hypothetical cases you cite have the same outcome: an innocent person is dead. In both cases the law is clear. Murder has been committed.