srgb - catch failed csv flash error

fixes CNVS-11634

test plan
- in srgb
- click upload CSV
- don't select a file, click upload
- verify that screenreader, JAWS read the flash error

Change-Id: I1fb82fd094e8ee4bcfd4878dd714ba76873449ac
Reviewed-on: https://gerrit.instructure.com/32950
Reviewed-by: Simon Williams <simon@instructure.com>
Tested-by: Jenkins <jenkins@instructure.com>
QA-Review: Amber Taniuchi <amber@instructure.com>
Product-Review: Aaron Cannon <acannon@instructure.com>