Merge pull request 'Update LCEssentials+API.swift' (#8) from fix/api/mainactor-session-hang into main

Reviewed-on: #8

Sources/LCEssentials/Classes/LCEssentials+API.swift

@@ -28,7 +28,6 @@ import Security
 #if canImport(UIKit)
 import UIKit
 #endif
-#endif
 
 /// A generic `Result` enumeration to represent either a success `Value` or a failure `Error`.
 public enum Result<Value, Error: Swift.Error> {
@@ -195,7 +194,18 @@ public struct API {
                 API.requestLOG(method: method, request: request)
             }
             
-            let session = URLSession(
+            // Only spin up a dedicated session (with its own @MainActor
+            // delegate hop for every TLS/auth challenge) when client
+            // certificate auth is actually configured. Creating one of
+            // these per request unconditionally — and never invalidating
+            // it — could stall the async challenge callback waiting on an
+            // already-busy MainActor, hanging the request indefinitely with
+            // no timeout or error ever surfacing. The common case (no
+            // client cert) uses the shared session, which has none of this
+            // risk and is what URLSession is designed to be reused as.
+            let usesCertSession = API.certData != nil
+            let session: URLSession = usesCertSession
+                ? URLSession(
                     configuration: .default,
                     delegate: URLSessionDelegateHandler(
                         certData: API.certData,
@@ -203,6 +213,12 @@ public struct API {
                     ),
                     delegateQueue: nil
                 )
+                : URLSession.shared
+            defer {
+                if usesCertSession {
+                    session.finishTasksAndInvalidate()
+                }
+            }
             do {
                 let (data, response) = try await session.data(for: request)