What was the mistake?
Leaving her son with a dog that has attacked a boy before? Her friends dog, so she likely knew.
Maybe the mistake was trusting her coke head friend? Whose was more insterested in smoking weed, doing coke and drinking than the potential consequences.
Do you trust people, who you know do this shit? Trust them enough to risk your child's life with?
Was the mistake, deciding to smoke weed, drink and snort coke while in sole charge of a minor? Leave him alone until 4.30am?
Non of those are mistakes. Those are choices. Her priority was getting smashed. Not the potential consequences to her child.
And no, it won't be the first time. It wouldn't have been the last either. How many times and from what age do you think she was leaving him to get high?
People who take coke do often lack a conscience and it becomes all consuming. They don't care about the crime associated with it. Tje sex trafficking, gun crime, knife crime, murders etc. They dont care they are neglecting their child so they can get off their face.
She broke the law. She neglected her child. Her neglect, led to her sons death. As a consequence, she went to prison. Thats how it works. She had a legal obligation to him.
If someone actions caused the death of a child that wasn't their biological child, i bet you would expect a prison sentance. But somehow its not needed because she is the mother?