Use Result-based continuation for JSRemote typed throws

Co-authored-by: Shelley <shelley@exe.dev>

Author: kateinoigakukun

Sources/JavaScriptEventLoop/JSRemote.swift

@@ -35,21 +35,11 @@ extension JSRemote where T == JSObject {
     public func withJSObject<R: Sendable, E: Error>(
         _ body: @Sendable @escaping (JSObject) throws(E) -> R
     ) async throws(E) -> sending R {
-        do {
-            return try await _withJSObjectAnyError(body)
-        } catch {
-            throw error as! E
-        }
-    }
-
-    private func _withJSObjectAnyError<R: Sendable>(
-        _ body: @Sendable @escaping (JSObject) throws(any Error) -> R
-    ) async throws -> sending R {
         #if _runtime(_multithreaded)
         if storage.sourceTid == swjs_get_worker_thread_id_cached() {
             return try body(storage.sourceObject)
         }
-        return try await withCheckedThrowingContinuation { continuation in
+        let result: Result<R, E> = await withCheckedContinuation { continuation in
             let context = _JSRemoteContext(
                 sourceObject: storage.sourceObject,
                 body: body,
@@ -60,6 +50,7 @@ extension JSRemote where T == JSObject {
                 Unmanaged.passRetained(context).toOpaque()
             )
         }
+        return try result.get()
         #else
         return try body(storage.sourceObject)
         #endif
@@ -95,17 +86,17 @@ private final class _JSRemoteContext: @unchecked Sendable {
     let invokeBody: () -> Bool
 
     #if compiler(>=6.4)
-    init<R: Sendable>(
+    init<R: Sendable, E: Error>(
         sourceObject: JSObject,
-        body: @escaping @Sendable (JSObject) throws(any Error) -> R,
-        continuation: CheckedContinuation<R, any Error>
+        body: @escaping @Sendable (JSObject) throws(E) -> R,
+        continuation: CheckedContinuation<Result<R, E>, Never>
     ) {
         self.invokeBody = {
             do {
-                continuation.resume(returning: try body(sourceObject))
+                continuation.resume(returning: .success(try body(sourceObject)))
                 return false
             } catch {
-                continuation.resume(throwing: error)
+                continuation.resume(returning: .failure(error as! E))
                 return true
             }
         }