When I speak to the Manillo fishing vendor at Chiqua and click to see his list of tradeable items, when I reach halfway down the list my game crashes. I'm just wondering if anyone else is having this issue, it's quite far into the game and other than speed up/slow down stuff it's generally been ok.

It's a bug and happen when you scroll down with controller plugged. Play it without and check if still crashes.

Sadly, GOG probably won't release a hotfix for this bug.

yeah, they won't since it's avoidable. I submitted bug report but it's always the automatic response, which means "nope, we won't read and fix"

Still crashed using just the keyboard

If it's Chiqua Manillo then probably due to the "Power Glove" bug. The forum doesn't allow me to post any links, you can search "Power Glove" and will see the topic

In rare occasion, you can buy "Power Glove" and equip it for Ershin without the crash. If you manage to do that, changing Ershin equipment will prone to crash too.