fix(#11315): don't call getLabelAndValue on null controller

[mihai-peteu]

Suggested fix for #11315

[mihai-peteu]

@etimberg | @LeeLenaleee
CI got snagged on a codeclimate check. I'm open to solutions on how to trim the function I touched down to 25 lines 😬

[LeeLenaleee]

It would be nice to have a test that shows this will fix it. Because I think you might shift the problem to other parts where the code expects values to be present which get set to null/undefined right now

[joshkel]

This change may have unintended effects. Currently, the TooltipItem type is defined as always providing a dataset. I experimented with this fix locally, any my code threw errors because my callbacks expected a dataset that was now not necessarily present.

I have an alternative candidate fix at #11596; I'm not sure if that approach is better or not.

[mihai-peteu]

Closing in favor of #11596