At the start of Professor Kristin Henning’s new book, “The Rage of Innocence: How America Criminalizes Black Youth” (Pantheon 2021), she shares the story of a former client she calls Eric, which is not his real name.Eric, a typical 13-year-old boy, was watching a movie, saw someone with a Molotov cocktail, and decided to build one. He put it together using household products including Pine-Sol and bleach, placed it in his backpack, and forgot about it. Fatefully, Eric went to school and school officials found it. As a …