more defensive code in shared.js in case server fails to re-add track
more defensive code in shared.js in case server fails to re-add track

pdaddyo/soundbounce,pdaddyo/soundbounce,pdaddyo/soundbounce,pdaddyo/soundbounce,viqueen/soundbounce,viqueen/soundbounce,viqueen/soundbounce,viqueen/soundbounce,pdaddyo/soundbounce,viqueen/soundbounce,viqueen/soundbounce,pdaddyo/soundbounce,pdaddyo/soundbounce,pdaddyo/soundbounce,viqueen/soundbounce,viqueen/soundbounce