Sadly there's not really a safe way to do this otherwise, but if you
really want to have persistence this way and absolutely need it to be
lock-free (because you're going to use it from the GUI thread), then you
can implement your own PersistentField.
I much prefer kebab case, but snake case is better here since Rust would
convert it to snake case when used as an identifier anyways and you also
can't use snake case modules without explicit module path attributes.
