fix(view-slot): correct null check against nextElementSibling
fix(view-slot): correct null check against nextElementSibling

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