RFR: 8279640: ListView with null SelectionModel/FocusModel throws NPE

[Marius Hanl]

On Wed, 10 Aug 2022 23:28:04 GMT, Andy Goryachev <angorya at openjdk.org> wrote:

> There is a condition observed while debugging [JDK-8187145](https://bugs.openjdk.org/browse/JDK-8187145), when a non-null selection model is set, the user creates a non-empty selection, then the selection is set to null.
> 
> The UI still shows selected cells - does the same bug exists in ListView?

Just tried and it looks fine for `ListView`.

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PR: https://git.openjdk.org/jfx/pull/711