custom_error_handler.php

<?php

function myCustomErrorHandler(int $errNo, string $errMsg, string $file, int $line) {
    echo "Wow my custom error handler got #[$errNo] occurred in [$file] at line [$line]: [$errMsg]";
}

set_error_handler('myCustomErrorHandler');

try {
  what;
} catch (Throwable $e) {
  echo 'And my error is: ' . $e->getMessage();
}