Record deserialization throws NRE if ignore null values is on #164
Description
Hello!
It seems there is some issue with the JsonRecordConverter: when ignoreNullValues is on (e.g. set with option DefaultIgnoreCondition = Serialization.JsonIgnoreCondition.WhenWritingNull), attempting to deserialize an empty json object throws a NullReferenceException.
I'm not sure how to fix this properly, but I managed to add a failing unit test demonstrating the issue: #165
