it-delete-read");
    gl.copyBufferSubData(gl.ARRAY_BUFFER, gl.COPY_WRITE_BUFFER, 0, 0, 8);
    await fence();
    deleteReadbackBuffer();
    checkGetBufferSubData(gl.INVALID_OPERATION, "noData");
    recreateReadbackBuffer();

    debug("");
    debug("write-fence-delete-wait-read");
    gl.copyBufferSubData(gl.ARRAY_BUFFER, gl.COPY_WRITE_BUFFER, 0, 0, 8);
    {
        const p = fence();
        deleteReadbackBuffer();
        await p;
    }
    checkGetBufferSubData(gl.INVALID_OPERATION, "noData");
    