log: fix panic when no loggers are in multilogger
log: fix panic when no loggers are in multilogger

guilhermebr/tsuru,ggarnier/tsuru,ArxdSilva/tsuru,guilhermebr/tsuru,ArxdSilva/tsuru,ArxdSilva/tsuru,tsuru/tsuru,cezarsa/tsuru,ggarnier/tsuru,tsuru/tsuru,cezarsa/tsuru,cezarsa/tsuru,cezarsa/tsuru,ggarnier/tsuru,guilhermebr/tsuru,tsuru/tsuru,tsuru/tsuru,guilhermebr/tsuru,ggarnier/tsuru,ArxdSilva/tsuru