I just got the same error while doing an Extreme Quest. I was doing Tundra & Automata stage 46-50, where stage 50 was a ??? stage. When I got to stage 50, it was getting ready to reveal what the stage mission would be, and then crashed before it could.
I've never gotten this error before nor have I had any other issues in the past, this is literally the first time I'm seeing this.
Edit: After this error occurred, I can no longer launch PSO2 (either via tweaker or default launcher), so I tried to restart my computer. My computer got stuck trying to restart and eventually blue screened before finally restarting.
Edit 2: So this error happened again today, seemingly at random. I'm beginning to suspect it has something to do with me using DS4Windows to use my PS4 controller on my PC instead of the Xbox 1 controller I had been using in the past. Especially considering the fact that once I get the np0 error, my controller just won't be detected, even after unplugging and replugging it via micro USB cable. The blue screen I get when I try to restart my computer after receiving this np0 error also may indicate an issue with the controller because the blue screen error is DRIVER_POWER_STATE_FAILURE. I never had an issue like this when using my Xbox 1 controller.