don't blow up if there are no assignments again
don't blow up if there are no assignments again

Change-Id: I0d4b2fc27daa7138719699153ee29cc2ee23f4fe
Reviewed-on: https://gerrit.instructure.com/62088
Reviewed-by: Jacob Fugal <f862f167b85d41b225785c70d70808bc7337c1fe@instructure.com>
Product-Review: Rob Orton <7e09c9d3e96378bf549fc283fd6e1e5b7014cc33@instructure.com>
QA-Review: Rob Orton <7e09c9d3e96378bf549fc283fd6e1e5b7014cc33@instructure.com>
Tested-by: Rob Orton <7e09c9d3e96378bf549fc283fd6e1e5b7014cc33@instructure.com>

kyroskoh/canvas-lms,skmezanul/canvas-lms,juoni/canvas-lms,sdeleon28/canvas-lms,jay3126/canvas-lms,sfu/canvas-lms,venturehive/canvas-lms,juoni/canvas-lms,leftplusrightllc/canvas-lms,sfu/canvas-lms,utkarshx/canvas-lms,HotChalk/canvas-lms,fronteerio/canvas-lms,sfu/canvas-lms,kyroskoh/canvas-lms,efrj/canvas-lms,tgroshon/canvas-lms,sfu/canvas-lms,sdeleon28/canvas-lms,leftplusrightllc/canvas-lms,antoniuslin/canvas-lms,efrj/canvas-lms,sdeleon28/canvas-lms,kyroskoh/canvas-lms,whalejasmine/canvas-lms,jay3126/canvas-lms,grahamb/canvas-lms,utkarshx/canvas-lms,redconfetti/canvas-lms,sfu/canvas-lms,juoni/canvas-lms,djbender/canvas-lms,efrj/canvas-lms,venturehive/canvas-lms,redconfetti/canvas-lms,jay3126/canvas-lms,roxolan/canvas-lms,skmezanul/canvas-lms,skmezanul/canvas-lms,HotChalk/canvas-lms,greyhwndz/canvas-lms,whalejasmine/canvas-lms,fronteerio/canvas-lms,efrj/canvas-lms,grahamb/canvas-lms,SwinburneOnline/canvas-lms,leftplusrightllc/canvas-lms,HotChalk/canvas-lms,tgroshon/canvas-lms,redconfetti/canvas-lms,whalejasmine/canvas-lms,whalejasmine/canvas-lms,utkarshx/canvas-lms,roxolan/canvas-lms,utkarshx/canvas-lms,venturehive/canvas-lms,grahamb/canvas-lms,tgroshon/canvas-lms,roxolan/canvas-lms,grahamb/canvas-lms,SwinburneOnline/canvas-lms,djbender/canvas-lms,tgroshon/canvas-lms,jay3126/canvas-lms,HotChalk/canvas-lms,sfu/canvas-lms,greyhwndz/canvas-lms,leftplusrightllc/canvas-lms,kyroskoh/canvas-lms,greyhwndz/canvas-lms,juoni/canvas-lms,grahamb/canvas-lms,sdeleon28/canvas-lms,venturehive/canvas-lms,skmezanul/canvas-lms,djbender/canvas-lms,fronteerio/canvas-lms,SwinburneOnline/canvas-lms,antoniuslin/canvas-lms,roxolan/canvas-lms,sfu/canvas-lms,greyhwndz/canvas-lms,redconfetti/canvas-lms,fronteerio/canvas-lms,antoniuslin/canvas-lms,antoniuslin/canvas-lms,djbender/canvas-lms,SwinburneOnline/canvas-lms