service/endpoint: fix Errorf call
service/endpoint: fix Errorf call

Thanks go  vet.

guilhermebr/tsuru,cezarsa/tsuru,guilhermebr/tsuru,tsuru/tsuru,ggarnier/tsuru,gwmoura/tsuru,ArxdSilva/tsuru,cezarsa/tsuru,tsuru/tsuru,cezarsa/tsuru,Endika/tsuru,Endika/tsuru,cezarsa/tsuru,ggarnier/tsuru,gwmoura/tsuru,gwmoura/tsuru,ggarnier/tsuru,Endika/tsuru,guilhermebr/tsuru,tsuru/tsuru,ArxdSilva/tsuru,ArxdSilva/tsuru,guilhermebr/tsuru,tsuru/tsuru,ggarnier/tsuru,ArxdSilva/tsuru