Make every field of CompletionStreamDataTrunk optional

Author: intitni

Tool/Sources/OpenAIService/ChatGPTService.swift

@@ -238,7 +238,7 @@ extension ChatGPTService {
                     cancelTask = cancel
                     let proposedId = UUID().uuidString
                     for try await trunk in trunks {
-                        guard let delta = trunk.choices.first?.delta else { continue }
+                        guard let delta = trunk.choices?.first?.delta else { continue }
 
                         // The api will always return a function call with JSON object.
                         // The first round will contain the function name and an empty argument.

Tool/Sources/OpenAIService/CompletionStreamAPI.swift

@@ -130,13 +130,13 @@ struct CompletionRequestBody: Encodable, Equatable {
 
 struct CompletionStreamDataTrunk: Codable {
     var id: String?
-    var object: String
-    var model: String
-    var choices: [Choice]
+    var object: String?
+    var model: String?
+    var choices: [Choice]?
 
     struct Choice: Codable {
-        var delta: Delta
-        var index: Int
+        var delta: Delta?
+        var index: Int?
         var finish_reason: String?
 
         struct Delta: Codable {