intentions

if a robber had intentions on robbinq a store but didn't, should the robber be punished for intentions ? he came in the lil chain man store w. the qun . took a deep breath in & out . proceeded to draw the qun but couldn't do it . he punk'd out . he just took a candy bar paid for it and left . how could you punish something like that ? locked up for a 18 months? take finqer prints for a just in case thinq?