Minor fixes

Library/Network/ExtensionErrors.swift

@@ -17,3 +17,11 @@ extension ExtensionStartupError: LocalizedError {
         message
     }
 }
+
+extension ExtensionStartupError: CustomNSError {
+    public static var errorDomain: String { "ExtensionStartupError" }
+    public var errorCode: Int { 1 }
+    public var errorUserInfo: [String: Any] {
+        [NSLocalizedDescriptionKey: message]
+    }
+}