/script run draw_shape('polygon',20,{'points'->[[0,100,0],[0,100,1],[1,100,1]]})
works in singleplayer (returns true and shows the polygon), but gives no output at all on servers. fabric-carpet-1.19.3-1.4.93+v221230

Do you have Carpet mod installed on both the server and client?

Yes. Spheres work as expected in both cases.

The problem is that, instead of just sending the shape to the client, you initialize the shape on the server first. Of course, not all rendering configurations are available on a standalone server ;)
Just replacing the enum values in question with their ordinal solves the issue.

@Environment(EnvType.CLIENT)
    public static enum Mode {
        LINES(4, 2, 2, false),
        LINE_STRIP(5, 2, 1, true),
        DEBUG_LINES(1, 2, 2, false),
        DEBUG_LINE_STRIP(3, 2, 1, true),
        TRIANGLES(4, 3, 3, false),
        TRIANGLE_STRIP(5, 3, 1, true),
        TRIANGLE_FAN(6, 3, 1, true),
        QUADS(4, 4, 4, false);
...

#1642

I'm surprised it doesn't crash the server if it's loading a client only class.

probably due to very broad catch around scarpet executions.

I think it warrants cherrypicking to 1.19.3

Then I think we should also backport #1635 and if it's based on the 1.19.3 branch it needs d9a4a62 as there's currently an NPE in there.