Oh, to build a D3 Panel 😮‍💨

Folks, I tried to install a panel with this fine tutorial.

Nice work, the original code in *SimplePanel.tsx as created by the

npx @grafana/toolkit plugin:create my-plugin
it just works!

However, whatever I do to the code in following the instructions in the tutorial, fails to compile with yarn dev. This even applies to the Complete Example
This fails with:
../grafana-plugins/my-plugin/src/SimplePanel.tsx 29:11 error Missing "key" prop for element in iterator react/jsx-key

I am wondering why does it not just work like the original code?
Also, in order to apply an official bundled datasource to this panel, is it necessary to create an App plugin?

Or is this at bleeding edge and only for the stout-hearted?

Thank you to any kind folk for taking a moment to assist with a working example.

Best wishes
Eric