I think it makes more sense if he uses the word chocolate as a metaphor for drugs so as not to sound too crude. The "simple mistake" is when he first got addicted (which is "the hardest time"). You know what he probably didn't have a clear idea of what it's about. It might have been about drugs or an affair to him. At the end of the day he probably didn't think we would sit and analyse it. I know some lines don't make much sense in my songs, sometimes they just rhyme!
I think it makes more sense if he uses the word chocolate as a metaphor for drugs so as not to sound too crude. The "simple mistake" is when he first got addicted (which is "the hardest time"). You know what he probably didn't have a clear idea of what it's about. It might have been about drugs or an affair to him. At the end of the day he probably didn't think we would sit and analyse it. I know some lines don't make much sense in my songs, sometimes they just rhyme!