Regression in setting vi mode

I think this used to work `config --set [edit_mode vi]` as per the PR that landed to add it, but if I try this now I get this error:

```
> config --set [edit_mode vi]
error: Error("unknown variant `vi`, expected one of `Primitive`, `Row`, `Binary`, `Table`, `Block`", line: 1, column: 63)
```