looking at the code, seems that error is in line (scan.c:1806):
if (!GTK_TOGGLE_BUTTON(ProcessFieldsDetectRomanNumerals)->active)
ProcessFieldsDetectRomanNumerals is a checkbox initialized at NULL. It's created at Scanner->Process Fields dialog, so I think that check its state before create it.
If you open the dialog before call the "First letter uppercase of each word" function it not crash.
looking at the code, seems that error is in line (scan.c:1806): BUTTON( ProcessFieldsDe tectRomanNumera ls)->active)
if (!GTK_TOGGLE_
ProcessFieldsDe tectRomanNumera ls is a checkbox initialized at NULL. It's created at Scanner->Process Fields dialog, so I think that check its state before create it.
If you open the dialog before call the "First letter uppercase of each word" function it not crash.