Fixed some issues detected by PHPstan.

src/Security/Voter/AttachmentVoter.php

@@ -34,14 +34,17 @@ class AttachmentVoter extends ExtendedVoter
      * Similar to voteOnAttribute, but checking for the anonymous user is already done.
      * The current user (or the anonymous user) is passed by $user.
      *
-     * @param $attribute
-     * @param $subject
+     * @param string $attribute
+     * @param mixed $subject
+     * @return bool
      */
     protected function voteOnUser($attribute, $subject, User $user): bool
     {
         if ($subject instanceof Attachment) {
             return $this->resolver->inherit($user, 'parts_attachments', $attribute) ?? false;
         }
+
+        return false;
     }
 
     /**

src/Security/Voter/ExtendedVoter.php

@@ -72,8 +72,9 @@ abstract class ExtendedVoter extends Voter
      * Similar to voteOnAttribute, but checking for the anonymous user is already done.
      * The current user (or the anonymous user) is passed by $user.
      *
-     * @param $attribute
-     * @param $subject
+     * @param string $attribute
+     * @param mixed $subject
+     * @return bool
      */
     abstract protected function voteOnUser($attribute, $subject, User $user): bool;
 }

src/Security/Voter/GroupVoter.php

@@ -33,8 +33,9 @@ class GroupVoter extends ExtendedVoter
      * Similar to voteOnAttribute, but checking for the anonymous user is already done.
      * The current user (or the anonymous user) is passed by $user.
      *
-     * @param $attribute
-     * @param $subject
+     * @param string $attribute
+     * @param mixed $subject
+     * @return bool
      */
     protected function voteOnUser($attribute, $subject, User $user): bool
     {

src/Security/Voter/PermissionVoter.php

@@ -37,8 +37,8 @@ class PermissionVoter extends ExtendedVoter
      * Similar to voteOnAttribute, but checking for the anonymous user is already done.
      * The current user (or the anonymous user) is passed by $user.
      *
-     * @param $attribute
-     * @param $subject
+     * @param string $attribute
+     * @param mixed $subject
      */
     protected function voteOnUser($attribute, $subject, User $user): bool
     {

src/Security/Voter/StructureVoter.php

@@ -54,6 +54,7 @@ class StructureVoter extends ExtendedVoter
             //If permission name is null, then the subject is not supported
             return (null !== $permission_name) && $this->resolver->isValidOperation($permission_name, $attribute);
         }
+        return false;
     }
 
     /**
@@ -94,8 +95,9 @@ class StructureVoter extends ExtendedVoter
      * Similar to voteOnAttribute, but checking for the anonymous user is already done.
      * The current user (or the anonymous user) is passed by $user.
      *
-     * @param $attribute
-     * @param $subject
+     * @param string $attribute
+     * @param mixed $subject
+     * @return bool
      */
     protected function voteOnUser($attribute, $subject, User $user): bool
     {

src/Security/Voter/UserVoter.php

@@ -54,8 +54,9 @@ class UserVoter extends ExtendedVoter
      * Similar to voteOnAttribute, but checking for the anonymous user is already done.
      * The current user (or the anonymous user) is passed by $user.
      *
-     * @param $attribute
-     * @param $subject
+     * @param string $attribute
+     * @param mixed $subject
+     * @return bool
      */
     protected function voteOnUser($attribute, $subject, User $user): bool
     {