fix: set `None` observer properly in `ScopedFuture`

reactive_graph/src/computed/async_derived/arc_async_derived.rs

@@ -9,7 +9,7 @@ use crate::{
     diagnostics::SpecialNonReactiveFuture,
     graph::{
         AnySource, AnySubscriber, ReactiveNode, Source, SourceSet, Subscriber,
-        SubscriberSet, ToAnySource, ToAnySubscriber,
+        SubscriberSet, ToAnySource, ToAnySubscriber, WithObserver,
     },
     owner::{use_context, Owner},
     signal::guards::{AsyncPlain, ReadGuard},

reactive_graph/src/computed/async_derived/mod.rs

@@ -5,7 +5,7 @@ mod async_derived;
 mod future_impls;
 mod inner;
 use crate::{
-    graph::{AnySubscriber, Observer},
+    graph::{AnySubscriber, Observer, WithObserver},
     owner::Owner,
 };
 pub use async_derived::*;
@@ -23,7 +23,7 @@ pin_project! {
     #[derive(Clone)]
     #[allow(missing_docs)]
     pub struct ScopedFuture<Fut> {
-        pub owner: Option<Owner>,
+        pub owner: Owner,
         pub observer: Option<AnySubscriber>,
         #[pin]
         pub fut: Fut,
@@ -34,7 +34,7 @@ impl<Fut> ScopedFuture<Fut> {
     /// Wraps the given `Future` by taking the current [`Owner`] and [`Observer`] and re-setting
     /// them as the active owner and observer every time the inner `Future` is polled.
     pub fn new(fut: Fut) -> Self {
-        let owner = Owner::current();
+        let owner = Owner::current().unwrap_or_default();
         let observer = Observer::get();
         Self {
             owner,
@@ -49,14 +49,8 @@ impl<Fut: Future> Future for ScopedFuture<Fut> {
 
     fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
         let this = self.project();
-        match (this.owner, this.observer) {
-            (None, None) => this.fut.poll(cx),
-            (None, Some(obs)) => obs.with_observer(|| this.fut.poll(cx)),
-            (Some(owner), None) => owner.with(|| this.fut.poll(cx)),
-            (Some(owner), Some(observer)) => {
-                owner.with(|| observer.with_observer(|| this.fut.poll(cx)))
-            }
-        }
+        this.owner
+            .with(|| this.observer.with_observer(|| this.fut.poll(cx)))
     }
 }
 

reactive_graph/src/computed/inner.rs

@@ -1,7 +1,7 @@
 use crate::{
     graph::{
         AnySource, AnySubscriber, Observer, ReactiveNode, ReactiveNodeState,
-        Source, SourceSet, Subscriber, SubscriberSet,
+        Source, SourceSet, Subscriber, SubscriberSet, WithObserver,
     },
     owner::Owner,
 };

reactive_graph/src/effect/effect.rs

@@ -3,6 +3,7 @@ use crate::{
     effect::inner::EffectInner,
     graph::{
         AnySubscriber, ReactiveNode, SourceSet, Subscriber, ToAnySubscriber,
+        WithObserver,
     },
     owner::{Owner, StoredValue},
     traits::Dispose,

reactive_graph/src/effect/render_effect.rs

@@ -3,6 +3,7 @@ use crate::{
     effect::inner::EffectInner,
     graph::{
         AnySubscriber, ReactiveNode, SourceSet, Subscriber, ToAnySubscriber,
+        WithObserver,
     },
     owner::Owner,
 };

reactive_graph/src/graph/subscriber.rs

@@ -13,6 +13,7 @@ thread_local! {
 /// subscribe to changes in any signals that are read.
 pub struct Observer;
 
+#[derive(Debug)]
 struct SetObserverOnDrop(Option<AnySubscriber>);
 
 impl Drop for SetObserverOnDrop {
@@ -39,10 +40,9 @@ impl Observer {
         OBSERVER.with_borrow_mut(|o| *o = observer);
     }
 
-    fn replace(observer: AnySubscriber) -> SetObserverOnDrop {
+    fn replace(observer: Option<AnySubscriber>) -> SetObserverOnDrop {
         SetObserverOnDrop(
-            OBSERVER
-                .with(|o| mem::replace(&mut *o.borrow_mut(), Some(observer))),
+            OBSERVER.with(|o| mem::replace(&mut *o.borrow_mut(), observer)),
         )
     }
 }
@@ -75,6 +75,7 @@ impl Observer {
 /// assert_eq!(c.get(), 3);
 /// # });
 /// ```
+#[track_caller]
 pub fn untrack<T>(fun: impl FnOnce() -> T) -> T {
     #[cfg(debug_assertions)]
     let _warning_guard = crate::diagnostics::SpecialNonReactiveZone::enter();
@@ -150,9 +151,23 @@ impl ReactiveNode for AnySubscriber {
     }
 }
 
-impl AnySubscriber {
+/// Runs code with some subscriber as the thread-local [`Observer`].
+pub trait WithObserver {
     /// Runs the given function with this subscriber as the thread-local [`Observer`].
-    pub fn with_observer<T>(&self, fun: impl FnOnce() -> T) -> T {
+    fn with_observer<T>(&self, fun: impl FnOnce() -> T) -> T;
+}
+
+impl WithObserver for AnySubscriber {
+    /// Runs the given function with this subscriber as the thread-local [`Observer`].
+    fn with_observer<T>(&self, fun: impl FnOnce() -> T) -> T {
+        let _prev = Observer::replace(Some(self.clone()));
+        fun()
+    }
+}
+
+impl WithObserver for Option<AnySubscriber> {
+    /// Runs the given function with this subscriber as the thread-local [`Observer`].
+    fn with_observer<T>(&self, fun: impl FnOnce() -> T) -> T {
         let _prev = Observer::replace(self.clone());
         fun()
     }