Via unascribed/BlockRenderer#28
Specifically via unascribed/BlockRenderer#28 (comment)

References:
https://stackoverflow.com/q/39809275
https://stackoverflow.com/a/54083335

BufferedImage initializes AWT which can't run on Mac if GLFW is running.

TODO:
Source Alternatives to our usages of BufferedImage / ImageIO for transforming the output / writing to file.
Source Alternatives to our GifWriter as this will also suffer from the same problems.

Document -Djava.awt.headless=true as a untested potential fix/mitigation for the current issues.

-Djava.awt.headless=true Shouldn't be needed as Mojang are already setting this programatically during startup, No idea what that actual issue with Mac's is at this point. Sourcing Alternatives has become slightly higher priority.

Note: LWJGL/lwjgl3#306 has some more information. Someone at Mojang also recentally checked if this was safe to do.