fix quiz show and edit pages

fixes CNVS-13320

test plan:
 - navigate to /quizzes
 > it should load without an error message
 - navigate to a single quiz (quizzes/:id)
 > it should load without an error message

Change-Id: Ic83f6ff6d5a9ae146057efb2418c8686cf52ec49
Reviewed-on: https://gerrit.instructure.com/35533
Reviewed-by: Liz Abinante <labinante@instructure.com>
QA-Review: Amber Taniuchi <amber@instructure.com>
Product-Review: Cameron Sutter <csutter@instructure.com>
Tested-by: Jenkins <jenkins@instructure.com>