Versioning of anvil.yaml schema

[owen.campbell]

In order to avoid problems like:

Unintended sharing of Users table between Environments -- how to fix?

Hi @p.colbert, Looks like you’re hitting an odd edge case! - sorry for the frustrating experience! This is happening because you set up your Users Service before we switched to identifying the user table by name. If you’re already hacking your YAML around, you can fix this pretty simply by changing {user_table: 61863} to {user_table: "users"}. That way your apps will start resolving the users table by name, and refer to the correct table in whatever environment it’s running in. More crudely, …

Could anvil.yaml have a version number and the runtime flag a warning if there’s a breaking change between current and the running app?

I’ve been bitten by this a couple of times now and it’s been a devil to chase down.