Does Jenny Slate really have “stage fright,” like her new Netflix comedy special claims? Upon first glance, it seems like an overmodest, even preposterous claim. Slate owns the stage with unbridled enthusiasm, glee, and a special brand of confidence. She absolutely radiates with self-love, laughing at her own riffs while saying, “I’m my biggest fan, I guess.” And yet, at the center of this uniquely bold stage presence lies a palpable sense of anxiety and, yes, fright, even before Slate starts tackling these issues explicitly. How did such a gulf between performing bravado and inner turmoil exist simultaneously? …