Kate suddenly not working

[D. R. Evans]

I was editing several things this afternoon, and suddenly, after
working fine for ages, kate stopped working.

Now when I invoke kate I get this on the console:
$ /usr/bin/kate
kio (KSycoca): Trying to open ksycoca from /var/tmp/kdecache-n7dr/ksycoca
kio (KTrader): query for KTextEditor/Plugin : returning 4 offers

Then nothing more happens :-(

Anyone any idea what's going on? I didn't change anything at all
between a Kate session that worked and then suddenly having it not
work :-(