First, big apologies that it asked you to upgrade to a beta! Especially a beta of a line that we've discontinued (we're going straight to v11).

This is now fixed, and I've added more automated testing to the versioning system.

As for this specific error, it looks like files for the ecommerce addon came back, which you'd uninstalled. So files, but no DB tables. I would guess this was caused by manually extracting the upgrade, or it already having a rogue addon_registry hook for that addon and it restoring the rest of the files. We're aiming to make this a problem of the past with v11 as it happens to too many people.

Or, the database upgrade step wasn't completed, as we renamed the invoices table to ecom_invoices.

Probably the latter as I haven't uninstalled any addons. How to fix?

You can go back into the upgrade and run the database upgrade step.