Don't dispatch script messages in an async context.

Source/Bridge.swift

@@ -173,9 +173,9 @@ public final class Bridge: Bridgable {
 }
 
 extension Bridge: ScriptMessageHandlerDelegate {
-    func scriptMessageHandlerDidReceiveMessage(_ scriptMessage: WKScriptMessage) async throws {
+    func scriptMessageHandlerDidReceiveMessage(_ scriptMessage: WKScriptMessage) {
         if let event = scriptMessage.body as? String, event == "ready" {
-            try await delegate?.bridgeDidInitialize()
+            delegate?.bridgeDidInitialize()
             return
         }
 
@@ -193,15 +193,14 @@ private extension WKWebView {
     /// in case the function doesn't return anything.
     /// This is a workaround. See https://forums.developer.apple.com/forums/thread/701553 for more details.
     @discardableResult
-    func evaluateJavaScriptAsync(_ str: String) async throws -> Any? {
+    @MainActor
+    func evaluateJavaScriptAsync(_ javaScriptString: String) async throws -> Any? {
         return try await withCheckedThrowingContinuation { (continuation: CheckedContinuation<Any?, Error>) in
-            DispatchQueue.main.async {
-                self.evaluateJavaScript(str) { data, error in
-                    if let error = error {
-                        continuation.resume(throwing: error)
-                    } else {
-                        continuation.resume(returning: data)
-                    }
+            evaluateJavaScript(javaScriptString) { data, error in
+                if let error {
+                    continuation.resume(throwing: error)
+                } else {
+                    continuation.resume(returning: data)
                 }
             }
         }

Source/BridgeDelegate.swift

@@ -21,7 +21,7 @@ public protocol BridgingDelegate: AnyObject {
 
     func component<C: BridgeComponent>() -> C?
 
-    func bridgeDidInitialize() async throws
+    func bridgeDidInitialize()
     func bridgeDidReceiveMessage(_ message: Message) -> Bool
 }
 
@@ -111,9 +111,15 @@ public final class BridgeDelegate: BridgingDelegate {
 
     // MARK: Internal use
 
-    public func bridgeDidInitialize() async throws {
+    public func bridgeDidInitialize() {
         let componentNames = componentTypes.map { $0.name }
-        try await bridge?.register(components: componentNames)
+        Task {
+            do {
+                try await bridge?.register(components: componentNames)
+            } catch {
+                logger.error("bridgeDidFailToRegisterComponents: \(error)")
+            }
+        }
     }
 
     @discardableResult

Source/ScriptMessageHandler.swift

@@ -1,7 +1,7 @@
 import WebKit
 
 protocol ScriptMessageHandlerDelegate: AnyObject {
-    func scriptMessageHandlerDidReceiveMessage(_ scriptMessage: WKScriptMessage) async throws
+    func scriptMessageHandlerDidReceiveMessage(_ scriptMessage: WKScriptMessage)
 }
 
 // Avoids retain cycle caused by WKUserContentController
@@ -13,6 +13,6 @@ final class ScriptMessageHandler: NSObject, WKScriptMessageHandler {
     }
 
     func userContentController(_ userContentController: WKUserContentController, didReceive scriptMessage: WKScriptMessage) {
-        Task { try await delegate?.scriptMessageHandlerDidReceiveMessage(scriptMessage) }
+        delegate?.scriptMessageHandlerDidReceiveMessage(scriptMessage)
     }
 }

Tests/BridgeDelegateTests.swift

@@ -24,8 +24,11 @@ class BridgeDelegateTests: XCTestCase {
     }
 
     func testBridgeDidInitialize() async throws {
-        try await delegate.bridgeDidInitialize()
-
+        await withCheckedContinuation { continuation in
+            bridge.registerComponentsContinuation = continuation
+            delegate.bridgeDidInitialize()
+        }
+
         XCTAssertTrue(bridge.registerComponentsWasCalled)
         XCTAssertEqual(bridge.registerComponentsArg, ["one", "two"])
 

Tests/Spies/BridgeDelegateSpy.swift

@@ -49,7 +49,7 @@ final class BridgeDelegateSpy: BridgingDelegate {
         return nil
     }
 
-    func bridgeDidInitialize() async throws {
+    func bridgeDidInitialize() {
 
     }
 

Tests/Spies/BridgeSpy.swift

@@ -9,7 +9,15 @@ final class BridgeSpy: Bridgable {
     var registerComponentWasCalled = false
     var registerComponentArg: String? = nil
 
-    var registerComponentsWasCalled = false
+    var registerComponentsWasCalled = false {
+        didSet {
+            if registerComponentsWasCalled {
+                registerComponentsContinuation?.resume()
+                registerComponentsContinuation = nil
+            }
+        }
+    }
+    var registerComponentsContinuation: CheckedContinuation<Void, Never>?
     var registerComponentsArg: [String]? = nil
 
     var unregisterComponentWasCalled = false