Raspberry Pi error in _sg_gl_create_buffer

This error occurs on a Raspberry Pi 4b running Debian 13 (trixie). It also occurs on Ubuntu ARM 26.04.1 under UTM on an ARM macbook pro, but does not occur on Fedora Asahi Remix running on an M1 macbook pro. I'm going to try to figure out what's happening, but I thought I'd post in case the cause is obvious to someone else.

I'm pulling sokol at 6b70854a and sokol-samples at ad0288e. I do:

cd sokol-samples/glfw
gcc cube-glfw.c glfw_glue.c flextgl33/flextGL.c -o cube-glfw -I../../sokol -lGL -ldl -lm -lglfw
./cube-glfw

(notice there are slight differences from the compile command in the sokol-samples readme -- the folder for flextgl and -lglfw because -lglfw3 doesn't exist).

The error I get is:

cube-glfw: ../../sokol/sokol_gfx.h:11113: _sg_gl_create_buffer: Assertion `gl_buf' failed

If I move the sg_make_buffer calls to after the sg_make_pipeline call (which I think is okay), I get an error when calling sg_make_pipeline too:

[sg][error][id:279] ../../sokol/sokol_gfx.h:24115:0: 
	VALIDATE_PIPELINEDESC_SHADER: sg_pipeline_desc.shader missing or invalid

[sg][panic][id:518] ../../sokol/sokol_gfx.h:23550:0: 
	VALIDATION_FAILED: validation layer checks failed