Fixes to app.html-in-webapp

- Depend on ui in webapp because we use UI.component

- Use eval rather than new Function because we *do* need the local
  environment (to get HTML, UI, etc)

- Log errors from running the template

These issues were not visible in normal apps because normal apps use
'ui' (implied by standard-app-packages) which makes UI a *global*. Ditto
for 'htmljs' (implied by ui) and the HTML symbol.