Fixed crash of ranking on anonymous user.
Fixed crash of ranking on anonymous user.

Phoenix1369/site,DMOJ/site,DMOJ/site,Minkov/site,Minkov/site,DMOJ/site,monouno/site,Minkov/site,Minkov/site,Phoenix1369/site,monouno/site,monouno/site,Phoenix1369/site,monouno/site,DMOJ/site,Phoenix1369/site,monouno/site