I'm on Mac and using the same build of Terragen and I don't get a crash when running check for updates.
Have you tried running Disk Utility on your mac?
It can be found from Launchpad on the bottom menu bar, then the folder called Others
click on it select your main hard drive (the one terragen is on) and click first aid. This will check for disc errors and any corrupted or out of place files. if it finds any it will attempt to fix them
Apple released a new update to safari, don't think it will cause any issues, but update it if you havent already.