[Distributed] whenLocal adoption of typed throws

whenLocal is a "rethrows" and can be expressed using a typed throw now.

Author: ktoso

stdlib/public/Distributed/DistributedActor.swift

@@ -362,9 +362,9 @@ extension DistributedActor {
   /// state.
   ///
   /// When the actor is remote, the closure won't be executed and this function will return nil.
-  public nonisolated func whenLocal<T: Sendable>(
-    _ body: @Sendable (isolated Self) async throws -> T
-  ) async rethrows -> T? {
+  public nonisolated func whenLocal<T: Sendable, E>(
+    _ body: @Sendable (isolated Self) async throws(E) -> T
+  ) async throws(E) -> T? {
     if __isLocalActor(self) {
        _local let localSelf = self
        return try await body(localSelf)