Fatal error: Uncaught TypeError: Unsupported operand types: string - int in /home/greg/learnmeabitcoin/src/explorer/Block.php:107 Stack trace: #0 /home/greg/learnmeabitcoin/src/explorer/Block.php(115): Explorer\Block->get_height_and_depth() #1 /home/greg/learnmeabitcoin/explorer/block/index.php(50): Explorer\Block->get_summary_and_header() #2 {main} thrown in /home/greg/learnmeabitcoin/src/explorer/Block.php on line 107