fix error on dev course reload in student emulation role; close #530
fix error on dev course reload in student emulation role; close #530

tbretl/PrairieLearn,parasgithub/PrairieLearn,parasgithub/PrairieLearn,mwest1066/PrairieLearn,rbessick5/PrairieLearn,mwest1066/PrairieLearn,parasgithub/PrairieLearn,mwest1066/PrairieLearn,PrairieLearn/PrairieLearnHack,PrairieLearn/PrairieLearnHack,PrairieLearn/PrairieLearnHack,kevinwang/PrairieLearn,jakebailey/PrairieLearn,PrairieLearn/PrairieLearnHack,tbretl/PrairieLearn,PrairieLearn/PrairieLearnHack,kevinwang/PrairieLearn,mwest1066/PrairieLearn,kevinwang/PrairieLearn,PrairieLearn/PrairieLearnHack,tbretl/PrairieLearn,kevinwang/PrairieLearn,rbessick5/PrairieLearn,kevinwang/PrairieLearn,parasgithub/PrairieLearn,jakebailey/PrairieLearn,PrairieLearn/PrairieLearnHack,kevinwang/PrairieLearn,tbretl/PrairieLearn,parasgithub/PrairieLearn,mwest1066/PrairieLearn,kevinwang/PrairieLearn,jakebailey/PrairieLearn,PrairieLearn/PrairieLearnHack,rbessick5/PrairieLearn,rbessick5/PrairieLearn,tbretl/PrairieLearn,jakebailey/PrairieLearn,rbessick5/PrairieLearn