This is due to a breaking change in php7
I have a patch I can submit that gets it working again or alternatively, everywhere you have variable variables eg $$all_options[‘second_order’] change it to ${$all_options[‘second_order’]}
The braces tells it to evaluate $all_options[‘second_order’] first as php7 would now evaluate $$all_options first then look for [‘second_order’] in that array. See php7 breaking changes for more info