notebook html_rendered does not support short profiling (no root frame).

[Carreau]

I'm working again on adding the options to the IPython magic;

Often nothing is shown in the html view with a:

about:srcdoc:14 Uncaught TypeError: Cannot read properties of null (reading 'identifier') (from Frame constructor)

I've tracked that down to:

class JSONForHTMLRenderer(FrameRenderer):
...
    def render(self, session: Session) -> str:
        
        frame_tree_json_str = root_frame.to_json_str() if root_frame else "null"  # here
        
		return '{"session": %s, "frame_tree": %s}' % (session_json_str, frame_tree_json_str)

And the svelt.typescript Session is not built to handle the case where frame_tree is null:

export default class Session {
   ...

    constructor(data: SessionData) {
        ...
        this.rootFrame = new Frame(data.frame_tree, this) // Frame don't like null.
    }

Ok, it's an edge case that should likely almost never happen a usualy user profile things that actually take time; but just letting you know.