merge tiny fix to prevent NPE apache#2955

Author: binary-signal

fluss-flink/fluss-flink-common/src/test/java/org/apache/fluss/flink/sink/FlussSinkITCase.java

@@ -383,11 +383,12 @@ public void testPartialUpdateWithTwoWriters() throws Exception {
                 for (ScanRecord record : scanRecords.records(bucket)) {
                     InternalRow row = record.getRow();
                     String address = row.getString(3) != null ? row.getString(3).toString() : null;
+                    int amount = row.isNullAt(2) ? -1 : row.getInt(2);
                     TestOrder order =
                             new TestOrder(
                                     row.getLong(0),
                                     row.getLong(1),
-                                    row.getInt(2),
+                                    amount,
                                     address,
                                     toFlinkRowKind(record.getChangeType()));
                     actual.add(order);