If you are on php 8.x, you may see this error: Deprecated function: mb_strlen(): Passing null to parameter #1 ($string) of type string is deprecated in Drupal\Component\Utility\Unicode::truncate() (line 313 of core/lib/Drupal/Component/Utility/Unicode.php).
This happens if null is passed as the first parameter to Unicode::truncate();.
Needs review
2.0
Code