fix(view-engine): double check existing on async load
fix(view-engine): double check existing on async load

behzad88/templating,JeroenVinke/templating,jdanyow/templating,jw56578/templating,michaelgeorgeattard/templating,aurelia/templating,simudream/templating,charlespockert/templating,cmichaelgraham/templating,hitesh97/templating,milunka/aurelia-templating,tcollard/templating,davismj/templating,aurelia/templating,shanonvl/aurelia-templating,PWKad/templating,AshleyGrant/templating