don't fire jstcss guard on sass errors
don't fire jstcss guard on sass errors

test plan:
1. put some invalid sass in a jst stylesheet
2. you should see the error in the guard output, but guard shouldn't die

Change-Id: Idd07ba3c64f89d35e79e3f6a886a28a26f8e8a1c
Reviewed-on: https://gerrit.instructure.com/24557
Reviewed-by: Mark Ericksen <776ab05fc6b68e82d2b2c63873bf56edde131809@instructure.com>
Reviewed-by: Landon Wilkins <e219b0c23c4256074cdfc7a23138e4f17200b08f@instructure.com>
Tested-by: Jenkins <d95b56ce41a2e1ac4cecdd398defd7414407cc08@instructure.com>
Product-Review: Jon Jensen <44f878afe53efc66b76772bd845eb65944ed8232@instructure.com>
QA-Review: Jon Jensen <44f878afe53efc66b76772bd845eb65944ed8232@instructure.com>

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