void re_yypop_buffer_state (yyscan_t yyscanner)
{
    struct yyguts_t * yyg = (struct yyguts_t*)yyscanner;
	if (!YY_CURRENT_BUFFER)
		return;

	re_yy_delete_buffer(YY_CURRENT_BUFFER ,yyscanner);
	YY_CURRENT_BUFFER_LVALUE = NULL;
	if (yyg->yy_buffer_stack_top > 0)
		--yyg->yy_buffer_stack_top;

	if (YY_CURRENT_BUFFER) {
		re_yy_load_buffer_state(yyscanner );
		yyg->yy_did_buffer_switch_on_eof = 1;
	}
}

The product dereferences a pointer that it expects to be valid but is NULL.