Set env variable from script and set next request | AssertionError: expected [] to have a length above +0 but got +0

i have finished the all the steps to achieve of the student expert of postman but I am having this Set env variable from script and set next request | AssertionError: expected [] to have a length above +0 but got +0 failure . i don’t know what I missed could you please someone help me . this is my Json link → https://www.getpostman.com/collections/b85a9e1f960df85c8f9c