https://bugs.winehq.org/show_bug.cgi?id=42845
--- Comment #15 from ttmigueltt@gmail.com --- And to summarise, the key issue seems to be this LocationAPI, which is only required by Hearthstone after clicking the Fireside Gatherings button (which makes sense, since it seems to be a feature for finding nearby players? I'm not certain, I've never used it). However once it's turned on, it's impossible to turn off, and will crash for that user whenever they log in to the same zone.
This LocationAPI must be a dotnet component that comes with dotnet 4.0, which only seems to install correctly in a 32-bit wine prefix, and thus installing it seems to resolve the issue.