CLI mode isn't headless (error: Unable to open DISPLAY)

[wajrou]

Describe the bug CLI mode doesn't work on Linux without X server.

To Reproduce

java --module-path /usr/share/openjfx/lib/ --add-modules ALL-MODULE-PATH -jar ~/bin/mcaselector-2.3.jar --mode cache --world ~/paper/world --zoom-level 1 --output ~/paper/map/world

exited immediately with:

error: Unable to open DISPLAY

Environment (please complete the following information):

• OS: Debian 11.9
• Java version:

  openjdk 17.0.10 2024-01-16
  OpenJDK Runtime Environment (build 17.0.10+7-Debian-1deb11u1)
  OpenJDK 64-Bit Server VM (build 17.0.10+7-Debian-1deb11u1, mixed mode, sharing)

• OpenJFX: 11.0.11
• Version of MCA Selector: 2.3