NK_list_devices() hangs with plugged in Nitrokey FIDO2 device

[daringer]

Bug report: The NK_list_devices() C-API call, while a Nitrokey FIDO2 device is plugged in, will never return and load one cpu.

How to reproduce:

• make sure you have a Nitrokey FIDO2 and a Nitrokey Pro (2) / Storage (2) plugged in
• libnitrokey and its headers must be installed
• create a file (and save it as nk.cc) with the following content:

  
  #include <libnitrokey/NK_C_API.h>
  #include <iostream>

using namespace std;

int main() { struct NK_device_info* x = NK_list_devices(); cout << x->model << endl; cout << x->path << endl; cout << x->serial_number << endl; }

* compile it using: `g++ nk.cc -o nk -lnitrokey -I/usr/include`
* run it: `./nk`

**Observed behavior:** The executable will hang inside the `NK_list_devices()` call

**Expected behavior:** The executable should return immediately, while ignoring any other devices 

**Environment:**
* Arch Linux (Kernel 5.9.12-arch1-1, AMD64)
* libnitrokey version 3.6 (package release 1)
* Nitrokey FIDO2 & Nitrokey Pro 2

[robin-nitrokey]

I have the same issue with libnitrokey 3.6 on Debian with kernel 5.10.0-0.bpo.4-amd64.