delay loading of subcomponents untill called

[RMHogervorst]

Loading of subcomponents is slow. What if we lazy eval and delay until actually needed.

https://stackoverflow.com/questions/35189760/using-delayed-assignment-in-a-function-how-do-i-send-the-promise-back-to-the-pa#35191961

https://rdocumentation.org/packages/base/versions/3.6.2/topics/delayedAssign

With a delayed assignment, or promise ( base R)