Well nevermind, fixed it in https://github.com/falkTX/wayland-audio-plugin-test/commit/ff9bdd884cfaeea95dd7402199a7741c39b7a727

(with some other little cleanup too)

basically I need to call "eglMakeCurrent(display, NULL, NULL, NULL);" to invalidate the GL context before deleting it.

everything works fine if this is the last thing the app does. crash happens if we create a new context after we delete one without "clearing" it first.