[BUGFIX] Return empty array when user can't be found

FrontendUserRepository::fetchUserInformationByEmail now returns
empty array when there is no user with given email.

Resolves: #92601
Releases: master, 10.4
Change-Id: Iad1d862de9e7c59879b4cfebdf15bc0d8e7fde55
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/66131
Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>

typo3/sysext/felogin/Classes/Domain/Repository/FrontendUserRepository.php

@@ -129,7 +129,8 @@ public function updateForgotHashForUserByEmail(string $emailAddress, string $has
     }
 
     /**
-     * Fetches array containing uid, username, email, first_name, middle_name & last_name by email.
+     * Fetches array containing uid, username, email, first_name, middle_name & last_name by email
+     * or empty array if user was not found.
      *
      * @param string $emailAddress
      * @return array
@@ -148,8 +149,11 @@ public function fetchUserInformationByEmail(string $emailAddress): array
                 )
             )
         ;
-
-        return $query->execute()->fetch(FetchMode::ASSOCIATIVE);
+        $result = $query->execute()->fetch(FetchMode::ASSOCIATIVE);
+        if (!is_array($result)) {
+            $result = [];
+        }
+        return $result;
     }
 
     /**

typo3/sysext/felogin/Tests/Functional/Domain/Repository/FrontendUserRepositoryTest.php

@@ -124,6 +124,10 @@ public function fetchUserInformationByEmailDataProvider(): array
                     'last_name' => '',
                 ]
             ],
+            'non existing user' => [
+                'non-existing@user.com',
+                []
+            ],
         ];
     }