Reactive Store panic when set during NodeRef::on_load

[seanaye]

Describe the bug
If you try to set the value of a reactive store during a NodeRef::on_load callback, there is a panic

tachys-0.1.7/src/reactive_graph/node_ref.rs:49:26:
called `Option::unwrap()` on a `None` value

Leptos Dependencies

For example:

leptos = { version = "0.7.7", features = ["nightly", "islands"] }
leptos_router = { version = "0.7.7", features = ["nightly"] }
axum = { version = "0.7", optional = true }
console_error_panic_hook = { version = "0.1", optional = true }
leptos_axum = { version = "0.7.7", optional = true }
leptos_meta = { version = "0.7.7" }
reactive_stores = { version = "0.1.7" }
tokio = { version = "1", features = ["rt-multi-thread"], optional = true }
wasm-bindgen = { version = "=0.2.100", optional = true }

To Reproduce
Steps to reproduce the behavior:

1. Checkout this repo
2. cargo leptos watch
3. open browser console
4. See error

Expected behavior
No panic should occur, the value in the store should be set

Screenshots

[gbj]

This one is actually due to NodeRef::on_load only being allowed to run once, but accidentally tracking reactive reads inside it (which .into_iter() on a keyed store subfield does). See #3686.