Bug id=142952, crashing mail merge

See https://bugs.documentfoundation.org/show_bug.cgi?id=142952 (Windows only, since 7.1). I’m sitting in front of a Windows PC with the latest LO 7.2.0.4. The crash happens when I confirm that I’m going to print a form letter but not while in safe mode. New profile, no user extensions. What else makes safe mode different?

I think earlier versions of LibreOffice 6.4 use OpenGL, while later versions of LibreOffice uses Skia. You could try disabling Skia and seeing if it works, Tools > Options > LibreOffice > View and untick Use Skia for all rendering. Cheers, Al
NB I think OpenCL is disabled in Safe mode as well as OpenGL/Skia

But I can’t repro using my debug build master, nor using a bibisect repo. So indeed, finding out which factor makes a difference here could be crucial to understand if being unable to repro is because it’s already somehow fixed in master, or because of the unknown factor.

(Maybe the factor is just an unmodified database recreated anew, without the query?)

I tried with dBase, Spreadsheet and external HSQL, both hardware accelleration and skia disabled.
It crashes when a datasource window is about to be displayed with a query. The mail merge dialog includes a datasource window and when I try to show the regular datasource window (Ctrl+Shift+F4) LO crashes as well because it tries to display the document’s data source. I have a feeling that the type of mail merge fields is not the culprit. It is the type of datasource that is about to be displayed.
How to do the trick with Calc (well, on my system at least):
Open the datasource window.
Drag a query icon from the left pane into a sheet.
Hide and unhide the datasource window. The application tries to open the datasource window with the query as active item and crashes. It does not crash if the source is a table.

Yes, that’s clear. What’s unclear is why it works in safe mode.

Bug reporter now says the crash went away in 7.2.2

Same PCs as always. Same profile as before. No crash anymore.