fix a bug in the jstcss guard
fix a bug in the jstcss guard

test plan:
with guard running:
edit a handlebars file that has a corresponding
sass file.
e.g.: app/views/jst/FolderTreeItem.handlebars

it should not crash guard

Change-Id: Icd04510dc4ac0ff80674d1b3116da0dccb199fd9
Reviewed-on: https://gerrit.instructure.com/41019
Tested-by: Jenkins <d95b56ce41a2e1ac4cecdd398defd7414407cc08@instructure.com>
Reviewed-by: Jeremy Stanley <b3f594e10a9edcf5413cf1190121d45078c62290@instructure.com>
Product-Review: Ryan Shaw <ea3cd978650417470535f3a4725b6b5042a6ab59@instructure.com>
QA-Review: Ryan Shaw <ea3cd978650417470535f3a4725b6b5042a6ab59@instructure.com>

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