Panic when interacting with a checkbox when the checked value is a `reactive_stores::Field` that is returned from a `at_unkeyed` call

[dzamlo]

The panic message is the following:

panicked at /home/dzamlo/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/reactive_graph-0.2.5/src/traits.rs:394:39:
At /home/dzamlo/.cargo/git/checkouts/thaw-bc232a1dca747192/33c18d9/thaw/src/checkbox/checkbox/mod.rs:69:41, you tried to access a reactive value which was defined at /home/dzamlo/.cargo/git/checkouts/thaw-bc232a1dca747192/33c18d9/thaw/src/checkbox/checkbox/mod.rs:36:25, but it has already been disposed.

Step to reproduce:

1. checkout the repo at https://github.com/dzamlo/checkbox-crash-reproduction.git
2. trunk serve --open
3. open the console in the browser
4. interact with the checkbox
5. see the panic in the console