Cannot use Jupyterlite in `thebe` 0.9.0-rc0

[stevejpurves]

Describe the bug

context
When I do initialize thebe with the useJuyterlite option.

expectation
I expected thebe to initialize and start Jupyterlite server

bug
But instead we get an error in the JS console

Reproduce the bug

Add thebe in a script tag
set useJupyterlite: true in the config

List your environment

No response

[stevejpurves]

Juptyerlite and all its dependencies load and work in thebe-core when bundled using webpack at that level.

This bug in thebe which consumes thebe-core looks like @lumino/commands does not get bundled properly. Looking at it in the browser devtools and CommandRegistry is undefined although the import does succeed.

[stevejpurves]

Changes to the bundling have been made which should get over the error reported above. Use of JuptyerLite is still blocked by this issue #575