Current master (KF5) crashes on closing.

[aga]

I get "Segmentation fault (core dumped)" on closing KMM.

At first, I thought it occurred if the CSV importer had been loaded, and
spent a long time trying to diagnose and solve it, without success.
This was initially using a clone from around 21 November.

Having today updated, again it crashes after the importer has been
loaded, but I then disabled the plugin via Settings. Then on closing,
again it crashes, but after a restart, no crash. However, still with the
plugin disabled, it again will crash on closing, if the KMM config menu
is opened and closed with nothing touched. And again on restart, but not
at the second attempt.

Then I opened the File menu, but made no selection.  On closing, no
crash.  Then open and close KMM.  No crash, nor on another restart, but
then it did crash on the next restart. Open the File menu and reload the
current file, then close, it's OK, but the next restart crashes.

I'm wondering if it might be to do with saving settings?

There is a crash dump, which is unhelpful to me, but no back trace.  In
fact, I haven't seen one of those for ages, for any crash, in fact
possibly since 4.8.

Allan