tolerate null caller in Logger.log
tolerate null caller in Logger.log

marcinolawski/avian,getlantern/avian,bigfatbrowncat/avian-pack.avian,bigfatbrowncat/avian-pack.avian,dicej/avian,joshuawarner32/avian,minor-jason/avian,getlantern/avian,marcinolawski/avian,dicej/avian,lwahlmeier/avian,ucdseniordesign/avian,MaartenR/avian,minor-jason/avian,lwahlmeier/avian,minor-jason/avian,bgould/avian,ucdseniordesign/avian,bgould/avian,MaartenR/avian,lwahlmeier/avian,joshuawarner32/avian,bgould/avian,dicej/avian,joshuawarner32/avian,getlantern/avian,lostdj/avian,badlogic/avian,badlogic/avian,ucdseniordesign/avian,dicej/avian,marcinolawski/avian,joshuawarner32/avian,badlogic/avian,bigfatbrowncat/avian-pack.avian,MaartenR/avian,lwahlmeier/avian,bgould/avian,marcinolawski/avian,badlogic/avian,minor-jason/avian,lostdj/avian,bigfatbrowncat/avian-pack.avian,getlantern/avian,ucdseniordesign/avian,lostdj/avian,lostdj/avian,MaartenR/avian