fix: filter out undefined instances when redrawing all charts

[web-padawan]

Description

Part of vaadin/flow-components#6607

This fixes the first part of the issue (reference error when redrawing all charts instances) by checking for undefined.

Type of change

• Bugfix

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[vaadin-bot]

Hi @web-padawan and @web-padawan, when i performed cherry-pick to this commit to 24.4, i have encountered the following issue. Can you take a look and pick it manually?
Error Message:
Error: Command failed: git cherry-pick 3e14d27
error: could not apply 3e14d27... fix: filter out undefined instances when redrawing all charts (#7779)
hint: After resolving the conflicts, mark them with
hint: "git add/rm ", then run
hint: "git cherry-pick --continue".
hint: You can instead skip this commit with "git cherry-pick --skip".
hint: To abort and get back to the state before "git cherry-pick",
hint: run "git cherry-pick --abort".

[vaadin-bot]

This ticket/PR has been released with Vaadin 24.5.0.beta2 and is also targeting the upcoming stable 24.5.0 version.