don't puke on missing saml attribute
don't puke on missing saml attribute

Change-Id: Ic829b81871d76d50090c930a57f836a42bd199a4
Reviewed-on: https://gerrit.instructure.com/60644
Tested-by: Jenkins
Reviewed-by: Rob Orton <7e09c9d3e96378bf549fc283fd6e1e5b7014cc33@instructure.com>
Product-Review: Cody Cutrer <c4fe2b1d90ef8f2548c8aeabfa633434316f0305@instructure.com>
QA-Review: Cody Cutrer <c4fe2b1d90ef8f2548c8aeabfa633434316f0305@instructure.com>

djbender/canvas-lms,jay3126/canvas-lms,leftplusrightllc/canvas-lms,grahamb/canvas-lms,redconfetti/canvas-lms,jay3126/canvas-lms,leftplusrightllc/canvas-lms,sfu/canvas-lms,dgynn/canvas-lms,venturehive/canvas-lms,leftplusrightllc/canvas-lms,AndranikMarkosyan/lms,snehakachroo1/LSI_replica,kyroskoh/canvas-lms,kyroskoh/canvas-lms,narigone/canvas,sfu/canvas-lms,snehakachroo1/LSI_replica,roxolan/canvas-lms,dgynn/canvas-lms,leftplusrightllc/canvas-lms,snehakachroo1/LSI_replica,HotChalk/canvas-lms,SwinburneOnline/canvas-lms,roxolan/canvas-lms,kyroskoh/canvas-lms,AndranikMarkosyan/lms,HotChalk/canvas-lms,redconfetti/canvas-lms,sfu/canvas-lms,venturehive/canvas-lms,dgynn/canvas-lms,roxolan/canvas-lms,redconfetti/canvas-lms,instructure/canvas-lms,roxolan/canvas-lms,jay3126/canvas-lms,grahamb/canvas-lms,grahamb/canvas-lms,AndranikMarkosyan/lms,instructure/canvas-lms,fronteerio/canvas-lms,djbender/canvas-lms,matematikk-mooc/canvas-lms,narigone/canvas,matematikk-mooc/canvas-lms,HotChalk/canvas-lms,fronteerio/canvas-lms,narigone/canvas,dgynn/canvas-lms,instructure/canvas-lms,redconfetti/canvas-lms,SwinburneOnline/canvas-lms,venturehive/canvas-lms,grahamb/canvas-lms,fronteerio/canvas-lms,sfu/canvas-lms,venturehive/canvas-lms,instructure/canvas-lms,grahamb/canvas-lms,jay3126/canvas-lms,instructure/canvas-lms,sfu/canvas-lms,SwinburneOnline/canvas-lms,djbender/canvas-lms,HotChalk/canvas-lms,snehakachroo1/LSI_replica,narigone/canvas,djbender/canvas-lms,AndranikMarkosyan/lms,instructure/canvas-lms,SwinburneOnline/canvas-lms,kyroskoh/canvas-lms,instructure/canvas-lms,fronteerio/canvas-lms,sfu/canvas-lms,matematikk-mooc/canvas-lms,sfu/canvas-lms,matematikk-mooc/canvas-lms