Merging nested arrays to csv when arrays are empty

[praveena1728]

I have data in json similar to the structure below:

[
{
        "incident": {
            "id": "120950002",
            "name": "Mosquito Fire"
        },
        "additionalClaimant": [
            {
                "claimantFirstName": "Olga",
                "claimantLastName": "Yachnik",

            },
           {
                "claimantFirstName": "Meera",
                "claimantLastName": "Lavina",

            },
        ]
},
{
        "incident": {
            "id": "120950002",
            "name": "Mosquito Fire"
        },
        "additionalClaimant": [],
},
]

The json contains an array called "AdditionalClaimant" which sometimes has value but also can be an empty array. I need to convert this to csv using ChoETL where the claimantFirstName values in the array should merge to one column ("Olga,Meera"). and this is my code

    //Use ChoETL to convert data to CSV
    using (var r = ChoJSONReader.LoadText(attorneyClaimData)
        .WithField("Fire", jsonPath: "$.incident.name", isArray: false)
        .WithField("FirstName", jsonPath: "$.additionalClaimant[*].claimantFirstName", defaultValue: "null")
    )
    {
        using (var w = new ChoCSVWriter("AttorneyClaims.csv")
            .WithFirstLineHeader()
            .UseNestedKeyFormat(false)
            .Configure(c => c.ArrayValueSeparator = ';')
            )
        {
            w.Write(r);
        }
    }

The problem arises when the AdditionalClaimant array is empty. I hit the error as below
"message": "Failed to write 'System.Object[]' value for 'FirstName' field."
Please can you help around how to navigate around this?

[Cinchoo]

Here is how you can convert your sample json to csv

        static void Issue304()
        {
            string json = @"[
  {
    ""incident"": {
      ""id"": ""120950002"",
      ""name"": ""Mosquito Fire""
    },
    ""additionalClaimant"": [
      {
        ""claimantFirstName"": ""Olga"",
        ""claimantLastName"": ""Yachnik""

      },
      {
        ""claimantFirstName"": ""Meera"",
        ""claimantLastName"": ""Lavina""

      }
    ]
  },
  {
    ""incident"": {
      ""id"": ""120950002"",
      ""name"": ""Mosquito Fire""
    },
    ""additionalClaimant"": []
  }
]";

            using (var r = ChoJSONReader.LoadText(json)
                .Configure(c => c.DefaultArrayHandling = false)
                .Configure(c => c.FlattenNode = true)
                .Configure(c => c.UseNestedKeyFormat = true)
                .Configure(c => c.FlattenByNodeName = "additionalClaimant")
                .Configure(c => c.NestedColumnSeparator = '.')
                )
            {
                using (var w = new ChoCSVWriter(Console.Out)
                    .WithFirstLineHeader()
                    )
                {
                    w.Write(r);
                }

            }
        }