Fix #794 by removing the length check because it's not always possibl…

…e to determine this.

src/Flurl.Http/Configuration/DefaultJsonSerializer.cs

@@ -35,6 +35,9 @@ public DefaultJsonSerializer(JsonSerializerOptions options = null) {
 		/// Deserializes the specified stream to an object of type T.
 		/// </summary>
 		/// <param name="stream">The stream to deserialize.</param>
-		public T Deserialize<T>(Stream stream) => stream.Length == 0 ? default : JsonSerializer.Deserialize<T>(stream, _options);
+		public T Deserialize<T>(Stream stream)
+		{
+			return JsonSerializer.Deserialize<T>(stream, _options);
+		}
 	}
-}
+}