The PHP exceptions' cheat sheet

                                    'fqcn' => \UnderflowException::class,
                                    'doc' => 'https://www.php.net/manual/en/class.underflowexception',
                                    'stackoverflow' => 'https://stackoverflow.com/q/69301995/633864',
                                    'parent' => \RuntimeException::class,
                                    'links' => ['https://airbrake.io/blog/php-exception-handling/underflowexception'],
                                ],
                                \UnexpectedValueException::class => [
                                    'fqcn' => \UnexpectedValueException::class,
                                    'doc' => 'https://www.php.net/manual/en/class.unexpectedvalueexception',
                                    'stackoverflow' => 'https://stackoverflow.com/q/34133049/633864',
                                    'parent' => \RuntimeException::class,
                                    'links' => ['https://airbrake.io/blog/php-exception-handling/unexpectedvalueexception-2'],
                                ],
                            ],
                        ],
                        \SoapFault::class => [
                            'fqcn' => \SoapFault::class,
                            'doc' => 'https://www.php.net/manual/en/soapfault.construct',
                            'stackoverflow' => 'https://stackoverflow.com/q/19612481/633864',
                            'parent' => \Exception::class,
                            'links' => ['https://hotexamples.com/examples/-/SoapFault/-/php-soapfault-class-examples.html'],
                        ],
                        \SodiumException::class => [
                            'fqcn' => \SodiumException::class,
                            'doc' => 'https://www.php.net/manual/en/class.sodiumexception',
                            'stackoverflow' => 'https://stackoverflow.com/q/54587528/633864',
                            'parent' => \Exception::class,
                        ],
                    ],
                ],
            ],
        ],
    ];

    /**
     * @return array<string>
     */
    private function listThrowableClasses(): array
    {
        $result = [];
        if (interface_exists('Throwable')) {
            foreach (get_declared_classes() as $cn) {
                $implements = class_implements($cn);
                if ($implements === false) {
                    continue;
                }

                if (isset($implements['Throwable'])) {
                    $result[] = $cn;
                }
            }
        } else {
            foreach (get_declared_classes() as $cn) {
                if ($cn === 'Exception' || is_subclass_of($cn, 'Exception')) {
                    $result[] = $cn;
                }
            }
        }

        return $result;
    }

    /**
     * @param array<string> $classes
     *
     * @return array<mixed>
     */
    private function groupByParents(array $classes): array
    {
        $result = [];
        foreach ($classes as $cn) {
            $parent = (string) get_parent_class($cn);
            if (isset($result[$parent])) {
                $result[$parent][] = $cn;
            } else {
                $result[$parent] = [$cn];
            }
        }

        return $result;
    }

    /**
     * @return array<mixed>
     */
    public function getExceptionsHierarchy(): array
    {
        $throwables = $this->listThrowableClasses();

        return $this->groupByParents($throwables);
    }

    public function printTree(): void
    {
        $tree = $this->getExceptionsHierarchy();

        // echo '<pre>';
        $this->printLeaves($tree, '', 0);
        // die();
    }

    /**
     * @param array<mixed> $tree
     */
    public function printLeaves(array &$tree, string $parent, int $level): void
    {
        if (isset($tree[$parent])) {
            /** @var array<string> $leaves */
            $leaves = $tree[$parent];
            unset($tree[$parent]);
            natcasesort($leaves);
            $leaves = array_values($leaves);
            foreach ($leaves as $leaf) {
                echo str_repeat('   ', $level), $leaf, "\n";
                $this->printLeaves($tree, $leaf, $level + 1);
            }
        }
    }
}