change how we build this error string
change how we build this error string

It's possible for an exception to have a nil message, in which case this
job worker process would die trying to do nil + "\n".

Change-Id: I7d6b4cb58fb47711e77ffc877b17f9248c401238
Reviewed-on: https://gerrit.instructure.com/16830
Tested-by: Jenkins <d95b56ce41a2e1ac4cecdd398defd7414407cc08@instructure.com>
Reviewed-by: Ethan Vizitei <0a27e12d062ad71673d57f9c2799b207af316885@12spokes.com>
QA-Review: Brian Palmer <3cb4e1df5ec4da2c7c4af7c52cec8cf340a55a10@instructure.com>

wimemx/Canvas,HotChalk/canvas-lms,fronteerio/canvas-lms,loganrun/pincan,snehakachroo1/LSI_replica,narigone/canvas,efrj/canvas-lms,SwinburneOnline/canvas-lms,arrivu/arrivu-lms,dgynn/canvas-lms,juoni/canvas-lms,fronteerio/canvas-lms,Unow/canvas-lms,Jyaasa/canvas-lms,kyroskoh/canvas-lms,parbros/red-innovadores-lms,narigone/canvas,efrj/canvas-lms,sdeleon28/canvas-lms,rup/Tarrax,narigone/canvas,utkarshx/canvas-lms,instructure/canvas-lms,leftplusrightllc/canvas-lms,fronteerio/canvas-lms,Rvor/canvas-lms,Unow/ins,dgynn/canvas-lms,fronteerio/canvas-lms,nditech/red-innovadores-lms,arrivu/hoodemo,va7map/canvas-lms,sfu/canvas-lms,Unow/canvas-lms,roxolan/canvas-lms,Rvor/canvas-lms,loganrun/pincan,AndranikMarkosyan/lms,roxolan/canvas-lms,arrivu/qibla-ecampus,landonwilkins/canvas-lms,arrivu/jigsaw-lms,nditech/red-innovadores-lms,venturehive/canvas-lms,antoniuslin/canvas-lms,eCNAP/CANVAS,redconfetti/canvas-lms,leftplusrightllc/canvas-lms,HotChalk/canvas-lms,djbender/canvas-lms,wye0220/shindig-canvas,antoniuslin/canvas-lms,Unow/canvas-lms,wimemx/Canvas,parbros/red-innovadores-lms,merichar/canvas-lms,SwinburneOnline/canvas-lms,arrivu/jigsaw-lms,narigone/canvas,dgynn/canvas-lms,Unow/ins,SwinburneOnline/canvas-lms,antoniuslin/canvas-lms,tgroshon/canvas-lms,nditech/red-innovadores-lms,instructure/canvas-lms,merichar/canvas-lms,HotChalk/canvas-lms,whalejasmine/canvas-lms,shidao-fm/canvas-lms,grahamb/canvas-lms,utkarshx/canvas-lms,jay3126/canvas-lms,instructure/canvas-lms,usmschuck/canvas,jay3126/canvas-lms,snehakachroo1/LSI_replica,greyhwndz/canvas-lms,shidao-fm/canvas-lms,loganrun/pincan,snehakachroo1/LSI_replica,sfu/canvas-lms,AndranikMarkosyan/lms,Rvor/canvas-lms,matematikk-mooc/canvas-lms,wye0220/shindig-canvas,usmschuck/canvas,roxolan/canvas-lms,sfu/canvas-lms,instructure/canvas-lms,matematikk-mooc/canvas-lms,usmschuck/canvas,ShreniiNepal/shrenii_lmp,instructure/canvas-lms,samuels410/greatlakes-lms,AndranikMarkosyan/lms,arrivu/jigsaw-lms,gbleydon/canvas-lms,arrivu/arrivu-lms,arrivu/qibla-ecampus,redconfetti/canvas-lms,utkarshx/canvas-lms,nditech/red-innovadores-lms,juoni/canvas-lms,Unow/ins,shidao-fm/canvas-lms,redconfetti/canvas-lms,jay3126/canvas-lms,wye0220/shindig-canvas,djbender/canvas-lms,parbros/red-innovadores-lms,eCNAP/CANVAS,whalejasmine/canvas-lms,gbleydon/canvas-lms,HotChalk/canvas-lms,skmezanul/canvas-lms,landonwilkins/canvas-lms,landonwilkins/canvas-lms,shidao-fm/canvas-lms,matematikk-mooc/canvas-lms,kyroskoh/canvas-lms,greyhwndz/canvas-lms,sdeleon28/canvas-lms,grahamb/canvas-lms,gbleydon/canvas-lms,efrj/canvas-lms,redconfetti/canvas-lms,AndranikMarkosyan/lms,instructure/canvas-lms,tgroshon/canvas-lms,wrdsb/canvas-lms,grahamb/canvas-lms,ShreniiNepal/shrenii_lmp,wrdsb/canvas-lms,sli7246/canvas_branch,juoni/canvas-lms,greyhwndz/canvas-lms,snehakachroo1/LSI_replica,djbender/canvas-lms,whalejasmine/canvas-lms,skmezanul/canvas-lms,tgroshon/canvas-lms,samuels410/greatlakes-lms,usmschuck/canvas,grahamb/canvas-lms,sfu/canvas-lms,sdeleon28/canvas-lms,Jyaasa/canvas-lms,ShreniiNepal/shrenii_lmp,skmezanul/canvas-lms,leftplusrightllc/canvas-lms,eCNAP/CANVAS,kyroskoh/canvas-lms,antoniuslin/canvas-lms,arrivu/qibla-ecampus,arrivu/arrivu-lms,arrivu/hoodemo,grahamb/canvas-lms,roxolan/canvas-lms,eCNAP/CANVAS,sli7246/canvas_branch,efrj/canvas-lms,skmezanul/canvas-lms,rup/Tarrax,SwinburneOnline/canvas-lms,dgynn/canvas-lms,jay3126/canvas-lms,juoni/canvas-lms,va7map/canvas-lms,utkarshx/canvas-lms,rup/Tarrax,Jyaasa/canvas-lms,venturehive/canvas-lms,wimemx/Canvas,wrdsb/canvas-lms,matematikk-mooc/canvas-lms,venturehive/canvas-lms,sfu/canvas-lms,sdeleon28/canvas-lms,va7map/canvas-lms,wrdsb/canvas-lms,va7map/canvas-lms,samuels410/greatlakes-lms,tgroshon/canvas-lms,instructure/canvas-lms,greyhwndz/canvas-lms,Rvor/canvas-lms,landonwilkins/canvas-lms,venturehive/canvas-lms,merichar/canvas-lms,Jyaasa/canvas-lms,arrivu/hoodemo,sli7246/canvas_branch,kyroskoh/canvas-lms,samuels410/greatlakes-lms,djbender/canvas-lms,whalejasmine/canvas-lms,sfu/canvas-lms,leftplusrightllc/canvas-lms,ShreniiNepal/shrenii_lmp,sfu/canvas-lms