Thanks for sharing this.  Looking forward to more. I spent a ludicrous amount of time chasing that and finally narrowed down the cause(s):  Alt-Tabbing and some mod (possibly Slavetats) that is passing data through json that doesn't fit json standard formatting and throws errors.  Giving the system a little while to settle after alt-tabbing usually fixes it for me now.  This is definitely related to json though, and Apropos2 "displays" the issue without directly causing it.