Same for me; the game just stopped with a Windows pop-up about lack of memory - for the first time ever.
Wasn’t doing anything that I haven’t done before a hundred times (I know for a fact that I’ve previously had much more stuff running on the PC at the same time with zero issues), PC is less than a year old, 32GB of RAM, all addons up to date.
This happened multiple times.
The only notable variable is that this took place in the pre-patch event zones (but like I said, I’ve levelled many, many characters during previous pre-patches with no issues and on less capable PCs)
No error code for me that I noticed.