Some minor changes

kordophone2/XPC/XPCClient.swift

@@ -148,9 +148,11 @@ final class XPCClient
         guard let reply = try await sendSync(req), xpc_get_type(reply) == XPC_TYPE_DICTIONARY else { throw Error.typeError }
 
         let fd = xpc_dictionary_dup_fd(reply, "fd")
-        if fd < 0 { throw Error.typeError }
+        let fileHandler = FileHandle(fileDescriptor: fd, closeOnDealloc: true)
         
-        return FileHandle(fileDescriptor: fd, closeOnDealloc: true)
+        if fd < 0 { throw Error.badFileHandle }
+        
+        return fileHandler
     }
 
     public func getSettings() async throws -> Serialized.Settings {
@@ -177,6 +179,7 @@ final class XPCClient
     {
         case typeError
         case encodingError
+        case badFileHandle
     }
     
     enum Signal