MM-18668: Fix for scan error selecting null SchemeGuest columns. (#12370)

store/sqlstore/group_store.go

@@ -977,7 +977,7 @@ func (s *SqlGroupStore) teamMembersMinusGroupMembersQuery(teamID string, groupID
 	if isCount {
 		selectStr = "count(DISTINCT Users.Id)"
 	} else {
-		tmpl := "Users.*, TeamMembers.SchemeGuest, TeamMembers.SchemeAdmin, TeamMembers.SchemeUser, %s AS GroupIDs"
+		tmpl := "Users.*, coalesce(TeamMembers.SchemeGuest, false), TeamMembers.SchemeAdmin, TeamMembers.SchemeUser, %s AS GroupIDs"
 		if s.DriverName() == model.DATABASE_DRIVER_MYSQL {
 			selectStr = fmt.Sprintf(tmpl, "group_concat(UserGroups.Id)")
 		} else {
@@ -1055,7 +1055,7 @@ func (s *SqlGroupStore) channelMembersMinusGroupMembersQuery(channelID string, g
 	if isCount {
 		selectStr = "count(DISTINCT Users.Id)"
 	} else {
-		tmpl := "Users.*, ChannelMembers.SchemeGuest, ChannelMembers.SchemeAdmin, ChannelMembers.SchemeUser, %s AS GroupIDs"
+		tmpl := "Users.*, coalesce(ChannelMembers.SchemeGuest, false), ChannelMembers.SchemeAdmin, ChannelMembers.SchemeUser, %s AS GroupIDs"
 		if s.DriverName() == model.DATABASE_DRIVER_MYSQL {
 			selectStr = fmt.Sprintf(tmpl, "group_concat(UserGroups.Id)")
 		} else {