That run an errand task doesn't make sense. All the other tasks were within Yvonne's power but this one puts all the control into Ellie's hands.
If this version wasn't rigged by Ellie herself then, what stops Ellie from just saying 'no' or leaving half-way forcing Yvonne to face the repercussions? That seems lika a kinda dumb mechanic.
First time seeing bullying, especially in anime/manga? In general, if a bully sends you on an errand, you do it or you face the repercussions. Possibly face them anyway when the bully finds a real or imaginary problem with the result. Leaving halfway only mean the next time you'll face much worse, and you can't hide forever when you need to go to school. Well, unless you take the option of becoming a shut-in never leaving your room. You think teachers will help? Even in the rare case they do, the harsher the bully's punishment, the worse their eventual vengeance.