MOBILE-1701 quiz: Don't show error if gradebook grade not found
MOBILE-1701 quiz: Don't show error if gradebook grade not found

Nithis111/AIT,NEEDS-SAL/SOrCEv3,chester666/moodlemobile,brenda10campos/GACER1,SathvikEdla/SathvikApp,arahimahmad/moodlemobile2,charterresources/sparkmobile2,romit19/SOrCEv3,balirwa/logs,arahimahmad/moodlemobile2,balirwa/logs,bmmg888/moodlemobile2,knurmi/MoodleTest,beppinu/moodleapp,bmmg888/moodlemobile2,NEEDS-SAL/SOrCEv3,mvvkiev/moodlemobile2,digidoug/fsdmoodle,dougrosa/eadinatel,romariox/moodlemobile2,Diaa75/moodlemobile2,bmmg888/moodlemobile2,charterresources/sparkmobile2,balirwa/logs,testvibid/imaritime,chester666/moodlemobile,dpaloucva/moodlemobile2,NEEDS-SAL/SOrCEv3,romit19/SOrCEv3,mohitsofat/mobiskool,GonzaloPachecoAlvarez/appteoloyu,salauddinias/jai,romariox/moodlemobile2,Andydadra/moodlemobile2,romit19/SOrCEv3,NEEDS-SAL/SOrCEv3,jnguy054/moodlemobile2,4emunoz/avcolsub,Diaa75/moodlemobile2,romit19/SOrCEv3,mohitsofat/mobiskool,MUPC-GH/MobileMoodle3.2.0,NEEDS-SAL/SOrCEv3,dpaloucva/moodlemobile2,MUPC-GH/MillikinMobileMoodle2,salauddinias/jai,NEEDS-SAL/SOrCEv3,romit19/SOrCEv3,arahimahmad/moodlemobile2,digidoug/fsdmoodle,Nithis111/AIT,sulzer/moodlemobile2,balirwa/logs,balirwa/logs,anludke/osborne-training-obs-app,GonzaloPachecoAlvarez/appteoloyu,4emunoz/avcolsub,chester666/moodlemobile,dougrosa/eadinatel,Andydadra/moodlemobile2,marceloalmeidasousa/moodleapp,MUPC-GH/MobileMoodle3.2.0,knurmi/MoodleTest,brenda10campos/GACER1,romit19/SOrCEv3,bmmg888/moodlemobile2,anludke/osborne-training-obs-app,salauddinias/jai-hind-app,marceloalmeidasousa/moodleapp,SathvikEdla/SathvikApp,beppinu/moodleapp,sulzer/moodlemobile2,MUPC-GH/MillikinMobileMoodle2,testvibid/imaritime,balirwa/logs,sulzer/moodlemobile2,salauddinias/jai-hind-app,mohitsofat/mobiskool,jnguy054/moodlemobile2,mvvkiev/moodlemobile2