cs: Use Collection more and fix potential duplicates.

src/Bundle/ChillPersonBundle/Controller/PersonApiController.php

@@ -22,6 +22,7 @@ use Sensio\Bundle\FrameworkExtraBundle\Configuration\ParamConverter;
 use Symfony\Component\HttpFoundation\Request;
 use Symfony\Component\HttpFoundation\Response;
 use Symfony\Component\Routing\Annotation\Route;
+use function in_array;
 
 class PersonApiController extends ApiController
 {
@@ -79,6 +80,8 @@ class PersonApiController extends ApiController
     {
         $this->denyAccessUnlessGranted(PersonVoter::SEE, $person);
 
+        $seenAddressIds = [];
+
         // collect addresses from location in courses
         $addresses = $person
             ->getAccompanyingPeriodParticipations()
@@ -91,13 +94,30 @@ class PersonApiController extends ApiController
                 static function (AccompanyingPeriodParticipation $accompanyingPeriodParticipation): ?Address {
                     return $accompanyingPeriodParticipation->getAccompanyingPeriod()->getAddressLocation();
                 }
+            )
+            ->filter(
+                // We remove potential null addresses.
+                static fn (?Address $address): bool => null !== $address
+            )
+            ->filter(
+                static function (Address $address) use (&$seenAddressIds): bool {
+                    $id = $address->getId();
+
+                    if (in_array($id, $seenAddressIds, true)) {
+                        return false;
+                    }
+
+                    $seenAddressIds[] = $id;
+
+                    return true;
+                }
             );
 
         // remove the actual address
         $actual = $person->getCurrentHouseholdAddress();
 
         if (null !== $actual) {
-            $addresses = $addresses->filter(static fn (?Address $address): bool => $address !== $actual);
+            $addresses = $addresses->filter(static fn (Address $address): bool => $address !== $actual);
         }
 
         return $this->json(