segmentation fault using QHeaderView::sectionSizeFromContents

Hi,

I already experienced multiple times a segmentation fault downstream QHeaderView::sectionSizeFromContents

Please see the attached screenshot

The call in QHeaderView::sectionSizeFromContents() on line 3061 results in a segmentation fault in QString::at() further down...

I think the problem is the result of d->model->headerData() is not checked on line 3053 and 3055.

Remark: opt.text is marked as <not accessible> and variant is marked (invalid)

On line 3037 and 3047 there is checking for a valid result!

I would add and extra check for the the d->model->headerData() result, but it is not clear to me that what happen when the result is invalid...

BUG QT-13082 looks quite similar