You can turn on a lot of logging in the ini file. That's usually a good place to start.
Crash dump can also help. Too lazy right now to look up the instructions I got for setting that up
There's also (with the cheatcode set in the ini file) ctrl + z to reveal everything and checking for anything out of the ordinary. The cause is often a city finishing production and the CtD occuring due to bad graphic references in the XML files.
If you suspect a certain part of the code is causing the problem you can add your own logging there. Don't remember right now what I use to log things, been a few weeks since I last touched FfH.
Crash dump can also help. Too lazy right now to look up the instructions I got for setting that up

There's also (with the cheatcode set in the ini file) ctrl + z to reveal everything and checking for anything out of the ordinary. The cause is often a city finishing production and the CtD occuring due to bad graphic references in the XML files.
If you suspect a certain part of the code is causing the problem you can add your own logging there. Don't remember right now what I use to log things, been a few weeks since I last touched FfH.