regression in charts introduced by one of the recent table to std::map commits

[Markus Mohrhard]

Hello Noel,

I just noticed that one of the following commits introduced a serious
regression in chart2. Can you please recheck them by opening the test
document in fdo#47632 and switch to edit mode. Then select one data
series and select the chart type menu entry in the pop-up menu. This
will immediately crash in chart2uno with a null pointer dereference.

3ffdb45ae047f12480e73fdd4b28fe35f1e8d48c
4aa72e0dee42c80667083c0b86a3d0ec5381c1ae
13bf19769e6e0522d920594225b9baa2c1b7dd63
6af00cf90f4314be11ac7d8f186bb9da4f228cf1
db3786ee3aa0d8911042c9bbcea02cf36d96dfa1

It would be great if you could have a look at them.

Regards,
Markus