Numpad buttons don't work on Linux #360

Version
2.0.0

Short overview
Calling keyboard.pressKey(nut.Key.NumPad1) doesn't work on Linux. It doesn't seem to work for any numpad key.

Issue occurs on

• Virtual machine
• Docker container
• Dev/Host system

Detailed error description

If you run the following code in Node.js 12.22.7 on Linux Mint 20.3 Cinnamon 20.3,

const nut = require("@nut-tree/nut-js");

nut.keyboard.pressKey(nut.Key.NumPad1);

the result of the last line will be rejected with this error:

Error: Invalid key code specified.
    at /wherever/node_modules/@nut-tree/nut-js/dist/lib/provider/native/libnut-keyboard.class.js:22:28

Steps to reproduce error

• Install Linux Mint Cinnamon 20.3
• Install Node.js 12.22.7.
• Create a file named test.js with the following content:

  const nut = require("@nut-tree/nut-js");
  
  nut.keyboard.pressKey(nut.Key.NumPad1);

• Open a terminal emulator and use cd to navigate to the folder where said script (test.js) resides.
• Type in node ./test.js

Expected behavior:

Numpad 1 gets pressed (virtually), so a "1" is typed into the terminal.

Actual behavior:

The key is not pressed, no "1" is typed into the terminal, and the following error is printed:

Error: Invalid key code specified.
    at /wherever/node_modules/@nut-tree/nut-js/dist/lib/provider/native/libnut-keyboard.class.js:22:28

Additional content

Please provide any (mandatory) additional data to reproduce the error (Dockerfiles etc.)

I am using a US keyboard layout, and my keyboard has a numpad. I also have a mouse attached that presents itself as both a mouse and a keyboard (because it has some macro keys on the side).

I am using Xorg, not wayland.

I have two monitors attached to my computer, and the primary monitor is on the right of the secondary monitor.