It's hard to know when/why a component is 'mis-specified'. Furthermore, my current debugging process is not ideal (app$layout_set(component); app$layout_get(); app$run_server()). Some ideas for improvements:

1. Printing a component could spin up a simple dash app with just that component.
2. Provide a 'debugging mode/option' where client side errors are listed in a pop-up (the current generic Error loading dependencies message is not helpful and most folks won't know to open their browser's dev tools)
3. Automatically type check arguments in R using the components propTypes definition