check for nil on RceCommandShim in case of double delete. don't except
check for nil on RceCommandShim in case of double delete. don't except

fixes CNVS-37279
fixes CNVS-37282

test plan:
- with RCS turned on, go to a course
- select "Outcomes"
- create a new outcome by clicking the "+ Outcome" button
- enter a name and text for the outcome
- click "Save"
- verify that it saves

Change-Id: I37edd29bd6e6dd8d97c1f64e84938fa9e8e7e013
Reviewed-on: https://gerrit.instructure.com/115154
Product-Review: brian kirkby <9a8a656cc2d0f066b1a373934e1a6a0652844ecd@instructure.com>
Tested-by: Jenkins
Reviewed-by: Tyler Pickett <3f20fcf21b1970c94966160adcf831eedd808a06@instructure.com>
QA-Review: Jeremy Putnam <b030d6d6f199f844ec424882be473c2ab9adc93b@instructure.com>

djbender/canvas-lms,venturehive/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,venturehive/canvas-lms,venturehive/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,venturehive/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,djbender/canvas-lms,djbender/canvas-lms,djbender/canvas-lms