Error with Dataset

```
What steps will reproduce the problem?
1. When the dataset has null values in the any columns it crashed
2.
3.

What is the expected output? What do you see instead?

What version of the product are you using? On what operating system?

Please provide any additional information below.

```

Original issue reported on code.google.com by `arrozev...@gmail.com` on 21 Jun 2011 at 4:11

The report says that null values in dataset columns cause a crash, but it names no source file, entry point, failing test, product version, or operating system. Start by reproducing the failure with a dataset containing null values, then locate the exception and add a regression test; done means such datasets no longer crash.

Written by the indexing model from the issue text.