Yosemite com.apple.xpc.launchd error every 10 seconds
Too bad i was posting before doing my own checking.

The solution was simple and shall be presented here for others who have the same issue: Simply launch Viber and go to Preferences, there, tell Viber not to launch on system startup. It will remove its LaunchDaemon entry and the error will disappear. 

Needless to say, Viber should address this issue in their first App release targeted for Yosemite OS X.