fix(athena-driver): Correct handling for NULL values (#6171)

Author: darapuk

packages/cubejs-athena-driver/src/AthenaDriver.ts

@@ -343,7 +343,8 @@ export class AthenaDriver extends BaseDriver implements DriverInterface {
         const fields: Record<string, any> = {};
         columnInfo
           .forEach((c, j) => {
-            fields[c.Name] = row.Data?.[j].VarCharValue;
+            const r = row.Data;
+            fields[c.Name] = (r === null || r === undefined || r[j].VarCharValue === undefined) ? null : r[j].VarCharValue;
           });
         yield fields as R;
       }

packages/cubejs-testing-shared/src/DriverTests.ts

@@ -34,6 +34,8 @@ export class DriverTests {
       SELECT 2 AS id, 200 AS amount, 'new' AS status
       UNION ALL
       SELECT 3 AS id, 400 AS amount, 'processed' AS status
+      UNION ALL
+      SELECT 4 AS id, 500 AS amount, NULL AS status
     ) AS data
     ORDER BY 1
   `;
@@ -42,6 +44,7 @@ export class DriverTests {
     { id: 1, amount: 100, status: 'new' },
     { id: 2, amount: 200, status: 'new' },
     { id: 3, amount: 400, status: 'processed' },
+    { id: 4, amount: 500, status: null },
   ];
 
   public static CSV_ROWS = dedent`