consistently does away with wasEmpty checks for TypeTrees
consistently does away with wasEmpty checks for TypeTrees

MasseGuillaume/scalameta,scalameta/scalameta,DavidDudson/scalameta,scalameta/scalameta,Dveim/scalameta,xeno-by/scalameta,xeno-by/scalameta,scalameta/scalameta,olafurpg/scalameta,scalameta/scalameta,MasseGuillaume/scalameta,olafurpg/scalameta,DavidDudson/scalameta,scalameta/scalameta,MasseGuillaume/scalameta,olafurpg/scalameta,xeno-by/scalameta