I don't know why it happened and can't reproduce it, but I'm reporting either way because the error message said to upload the log here

I was finishing the steel lanes and placed a splitter and then a belt after that and got the crash.
More context that might be useful:
I have a browser with some tabs and a twitch stream running in the background, no other cpu intensive process that I'm aware.
I have the base game without the DLC, want to feel like I beat the game properly before playing space age.
Uploaded my latest save file, the latest autosave file, the factorio-current.log and a summary system information that Steam provides.
Let me know if I can help with anything else.