Fix #433, #358, #342.

src/Custom/Chat/ChatFinishReason.cs

@@ -84,4 +84,12 @@ public enum ChatFinishReason
     /// </remarks>
     [CodeGenMember("FunctionCall")]
     FunctionCall,
+
+    /// <summary>
+    /// Indicates that the model returns unknown finish reason (or null).
+    /// We interpret this as a stop sequence.
+    /// </summary>
+    [CodeGenMember("Stop")]
+    Unknown
+
 }

src/Custom/Chat/Internal/InternalChatCompletionMessageToolCallFunction.Serialization.cs

@@ -25,6 +25,15 @@ private void SerializeArgumentsValue(Utf8JsonWriter writer, ModelReaderWriterOpt
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     private static void DeserializeArgumentsValue(JsonProperty property, ref BinaryData arguments, ModelReaderWriterOptions options = null)
     {
-        arguments = BinaryData.FromString(property.Value.GetString());
+        //for a tool calls without arguments there will be an Object instead of String.
+        var obj = property.Value.GetObject();
+        if (obj is string s)
+        {
+            arguments = BinaryData.FromString(s);
+        }
+        else
+        {
+            arguments = BinaryData.FromString(string.Empty);
+        }
     }
 }

src/Custom/Chat/Streaming/InternalChatCompletionMessageToolCallChunkFunction.Serialization.cs

@@ -26,6 +26,16 @@ private static void DeserializeArgumentsValue(JsonProperty property, ref BinaryD
         {
             return;
         }
-        arguments = BinaryData.FromString(property.Value.GetString());
+
+        //for a tool calls without arguments there will be an Object instead of String.
+        var obj = property.Value.GetObject();
+        if (obj is string s)
+        {
+            arguments = BinaryData.FromString(s);
+        }
+        else
+        {
+            arguments = BinaryData.FromString(string.Empty);
+        }
     }
 }

src/Generated/Models/ChatFinishReason.Serialization.cs

@@ -40,7 +40,7 @@ public static ChatFinishReason ToChatFinishReason(this string value)
             {
                 return ChatFinishReason.FunctionCall;
             }
-            throw new ArgumentOutOfRangeException(nameof(value), value, "Unknown ChatFinishReason value.");
+            return ChatFinishReason.Unknown;
         }
     }
 }