fix(csharp/src/Drivers/BigQuery): return null on GetValue exception (#…

…1562)

In a query such as `SELECT * FROM
bigquery-public-data.fhir_synthea.explanation_of_benefit`, a number of
items return null inside of the StructArray result. An exception is
thrown from the underlying Arrow calls because we hit a scenario where
Length and index are both 0, so an `ArgumentOutOfRangeException` is
thrown per
https://github.com/apache/arrow/blob/280bc112b23976d2f17c07c638bb62702ac89e8a/csharp/src/Apache.Arrow/Arrays/BinaryArray.cs#L356.

---------

Co-authored-by: David Coe <coedavid@umich.edu>

csharp/src/Drivers/BigQuery/BigQueryConnection.cs

@@ -85,8 +85,11 @@ internal void Open()
             if (!this.properties.TryGetValue(BigQueryParameters.ProjectId, out projectId))
                 throw new ArgumentException($"The {BigQueryParameters.ProjectId} parameter is not present");
 
-            if (this.properties.TryGetValue(BigQueryParameters.AuthenticationType, out authenticationType))
+            if (this.properties.TryGetValue(BigQueryParameters.AuthenticationType, out string? newAuthenticationType))
             {
+                if (!string.IsNullOrEmpty(newAuthenticationType))
+                    authenticationType = newAuthenticationType;
+
                 if (!authenticationType.Equals(BigQueryConstants.UserAuthenticationType, StringComparison.OrdinalIgnoreCase) &&
                     !authenticationType.Equals(BigQueryConstants.ServiceAccountAuthenticationType, StringComparison.OrdinalIgnoreCase))
                 {

csharp/src/Drivers/BigQuery/BigQueryStatement.cs

@@ -233,6 +233,9 @@ private string SerializeToJson(StructArray structArray, int index)
 
         private Dictionary<String, object> ParseStructArray(StructArray structArray, int index)
         {
+            if (structArray.IsNull(index))
+                return null;
+
             Dictionary<String, object> jsonDictionary = new Dictionary<String, object>();
             StructType structType = (StructType)structArray.Data.DataType;
             for (int i = 0; i < structArray.Data.Children.Length; i++)