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PHP exceptions extend \Throwable. Use try/catch/finally:

try {
    $data = parseConfig($input);
} catch (JsonException $e) {
    error_log("bad json: " . $e->getMessage());
    return null;
} catch (\Exception $e) {
    error_log("unexpected: " . $e->getMessage());
    throw $e;       // re-throw
} finally {
    cleanup();
}

Multi-catch — one block for several unrelated types. It landed in PHP 7.1, so it works on this course's 7.4 grader:

try { ... }
catch (\JsonException | \RuntimeException $e) { ... }

What is not on 7.4 is \ValueError (PHP 8) — reach for \InvalidArgumentException there. When the types you want share a parent, catching the ancestor is still the shorter spelling:

catch (\RuntimeException $e) { ... }

Custom exceptions — extend \Exception (or \RuntimeException):

class ValidationException extends \Exception {
    public string $field;

    public function __construct(string $field, string $msg = '') {
        $this->field = $field;
        parent::__construct($msg ?: "missing $field");
    }
}

throw new ValidationException('email');

Declaring the property and assigning it in the constructor body looks verbose next to PHP 8's constructor property promotion (__construct(public string $field)) — but promotion is a parse error on 7.4, so this longhand is what the grader accepts.

Useful built-in exceptions:

• \InvalidArgumentException — bad parameter
• \OutOfRangeException — index out of bounds
• \RuntimeException — error at runtime that couldn't be predicted
• \LogicException — programmer error (should have caught at dev time)

Throwable is the root — both Exception and Error (engine errors like TypeError) implement it. Catch \Throwable only at the topmost layer.