Fix crash reported by app insights (#1197)
Fix crash reported by app insights (#1197)


playi/pxt,switchinnovations/pxt,switch-education/pxt,switch-education/pxt,switchinnovations/pxt,switchinnovations/pxt,playi/pxt,playi/pxt,switchinnovations/pxt,Microsoft/pxt,switch-education/pxt,Microsoft/pxt,playi/pxt,switch-education/pxt,Microsoft/pxt,Microsoft/pxt,switch-education/pxt,Microsoft/pxt