fixed crash when group is not included in any category
fixed crash when group is not included in any category

cloverstudio/Spika-iOS,trd-delarajon/Spika-IOS,trd-delarajon/Spika-IOS,cloverstudio/Spika-iOS,trd-delarajon/Spika-IOS,cloverstudio/Spika-iOS,trd-delarajon/Spika-IOS