Fix routing of leader updates from unshared projects

Previously, leader updates in unshared projects would be sent to
all followers regardless of project, as if they were not scoped
to any project.

crates/util/src/util.rs

@@ -137,6 +137,8 @@ pub trait ResultExt<E> {
     type Ok;
 
     fn log_err(self) -> Option<Self::Ok>;
+    /// Assert that this result should never be an error in development or tests.
+    fn debug_assert_ok(self, reason: &str) -> Self;
     fn warn_on_err(self) -> Option<Self::Ok>;
     fn inspect_error(self, func: impl FnOnce(&E)) -> Self;
 }
@@ -159,6 +161,14 @@ where
         }
     }
 
+    #[track_caller]
+    fn debug_assert_ok(self, reason: &str) -> Self {
+        if let Err(error) = &self {
+            debug_panic!("{reason} - {error:?}");
+        }
+        self
+    }
+
     fn warn_on_err(self) -> Option<T> {
         match self {
             Ok(value) => Some(value),