Minor refactoring

SignalServiceKit/src/Loki/API/HTTP/HTTP.swift

@@ -41,18 +41,18 @@ internal enum HTTP {
 
     // MARK: Main
     internal static func execute(_ verb: Verb, _ url: String, parameters: JSON? = nil, timeout: TimeInterval = HTTP.timeout) -> Promise<JSON> {
-        return Promise<JSON> { seal in
         var request = URLRequest(url: URL(string: url)!)
         request.httpMethod = verb.rawValue
         if let parameters = parameters {
             do {
-                    guard JSONSerialization.isValidJSONObject(parameters) else { return seal.reject(Error.invalidJSON) }
+                guard JSONSerialization.isValidJSONObject(parameters) else { return Promise(error: Error.invalidJSON) }
                 request.httpBody = try JSONSerialization.data(withJSONObject: parameters, options: [])
             } catch (let error) {
-                    return seal.reject(error)
+                return Promise(error: error)
             }
         }
         request.timeoutInterval = timeout
+        let (promise, seal) = Promise<JSON>.pending()
         let task = urlSession.dataTask(with: request) { data, response, error in
             guard let data = data, let response = response as? HTTPURLResponse else {
                 if let error = error {
@@ -88,6 +88,6 @@ internal enum HTTP {
             }
         }
         task.resume()
-        }
+        return promise
     }
 }