[jfx22] RFR: 8323543: NPE when table items are set to null

[Marius Hanl]

This pull request contains a (clean) backport of commit [872dbc8a](https://github.com/openjdk/jfx/commit/872dbc8a2d254cba4df33fcc778b15b1a3c9b69f) from the [openjdk/jfx](https://git.openjdk.org/jfx) repository.

Target branch is **jfx22**.

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Commit messages:
 - Backport 872dbc8a2d254cba4df33fcc778b15b1a3c9b69f

Changes: https://git.openjdk.org/jfx/pull/1341/files
 Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=1341&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8323543
  Stats: 60 lines in 5 files changed: 47 ins; 11 del; 2 mod
  Patch: https://git.openjdk.org/jfx/pull/1341.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1341/head:pull/1341

PR: https://git.openjdk.org/jfx/pull/1341