diff --git a/app/Console/Commands/Storage/SetupDropboxStorageCommand.php b/app/Console/Commands/Storage/SetupDropboxStorageCommand.php
index 36a9a8e9..929aa96c 100644
--- a/app/Console/Commands/Storage/SetupDropboxStorageCommand.php
+++ b/app/Console/Commands/Storage/SetupDropboxStorageCommand.php
@@ -55,7 +55,7 @@ class SetupDropboxStorageCommand extends Command
         $accessCode = $this->ask('Enter the access code');
 
         $response = Http::asForm()
-            ->withBasicAuth($appKey, $appSecret)
+            ->withBasicAuth($config['DROPBOX_APP_KEY'], $config['DROPBOX_APP_SECRET'])
             ->post('https://api.dropboxapi.com/oauth2/token', [
                 'code' => $accessCode,
                 'grant_type' => 'authorization_code',
diff --git a/app/Exceptions/UnsupportedSongStorageTypeException.php b/app/Exceptions/UnsupportedSongStorageTypeException.php
index 9ee7e3e2..93958760 100644
--- a/app/Exceptions/UnsupportedSongStorageTypeException.php
+++ b/app/Exceptions/UnsupportedSongStorageTypeException.php
@@ -11,7 +11,7 @@ class UnsupportedSongStorageTypeException extends Exception
         parent::__construct("Unsupported song storage type: $storageType");
     }
 
-    public function create(string $storageType): self
+    public static function create(string $storageType): self
     {
         return new self($storageType);
     }
diff --git a/app/Http/Controllers/API/PlaylistCollaboration/PlaylistCollaboratorController.php b/app/Http/Controllers/API/PlaylistCollaboration/PlaylistCollaboratorController.php
index 70a2ca58..65aa3320 100644
--- a/app/Http/Controllers/API/PlaylistCollaboration/PlaylistCollaboratorController.php
+++ b/app/Http/Controllers/API/PlaylistCollaboration/PlaylistCollaboratorController.php
@@ -15,7 +15,6 @@ use Illuminate\Http\Response;
 
 class PlaylistCollaboratorController extends Controller
 {
-    /** @param User $user */
     public function __construct(private PlaylistCollaborationService $service, private UserRepository $userRepository)
     {
     }
diff --git a/app/Models/Playlist.php b/app/Models/Playlist.php
index e0eced09..704a603a 100644
--- a/app/Models/Playlist.php
+++ b/app/Models/Playlist.php
@@ -63,7 +63,8 @@ class Playlist extends Model
 
     public function songs(): BelongsToMany
     {
-        return $this->belongsToMany(Song::class)->withTimestamps()
+        return $this->belongsToMany(Song::class)
+            ->withTimestamps()
             ->withPivot('position')
             ->orderByPivot('position');
     }
@@ -160,7 +161,7 @@ class Playlist extends Model
     public function addSongs(Collection|Song|array $songs, ?User $collaborator = null): void
     {
         $collaborator ??= $this->user;
-        $maxPosition = $this->songs()->max('position') ?? 0;
+        $maxPosition = $this->songs()->getQuery()->max('position') ?? 0;
 
         if (!is_array($songs)) {
             $songs = Collection::wrap($songs)->pluck('id')->all();
diff --git a/app/Services/Streamer/Streamer.php b/app/Services/Streamer/Streamer.php
index 0792e337..999a1cb3 100644
--- a/app/Services/Streamer/Streamer.php
+++ b/app/Services/Streamer/Streamer.php
@@ -39,7 +39,7 @@ class Streamer
             SongStorageTypes::LOCAL, '' => app(LocalStreamerAdapter::class),
             SongStorageTypes::S3, SongStorageTypes::S3_LAMBDA => app(S3CompatibleStreamerAdapter::class),
             SongStorageTypes::DROPBOX => app(DropboxStreamerAdapter::class),
-            default => throw UnsupportedSongStorageTypeException::make($this->song->storage),
+            default => throw UnsupportedSongStorageTypeException::create($this->song->storage),
         };
     }
 
diff --git a/app/Values/Equalizer.php b/app/Values/Equalizer.php
index 44c60e2b..e1da2436 100644
--- a/app/Values/Equalizer.php
+++ b/app/Values/Equalizer.php
@@ -9,7 +9,7 @@ use Throwable;
 final class Equalizer implements Arrayable
 {
     /** @param array<int>|null $gains */
-    private function __construct(public ?string $name, public int $preamp, public array $gains)
+    private function __construct(public ?string $name, public ?int $preamp, public ?array $gains)
     {
     }
 
diff --git a/tests/Feature/KoelPlus/AlbumCoverTest.php b/tests/Feature/KoelPlus/AlbumCoverTest.php
index efca63d7..77560bdf 100644
--- a/tests/Feature/KoelPlus/AlbumCoverTest.php
+++ b/tests/Feature/KoelPlus/AlbumCoverTest.php
@@ -6,6 +6,7 @@ use App\Models\Album;
 use App\Models\Song;
 use App\Services\MediaMetadataService;
 use Mockery;
+use Mockery\MockInterface;
 use Tests\PlusTestCase;
 
 use function Tests\create_admin;
@@ -13,6 +14,8 @@ use function Tests\create_user;
 
 class AlbumCoverTest extends PlusTestCase
 {
+    private MediaMetadataService|MockInterface $mediaMetadataService;
+
     public function setUp(): void
     {
         parent::setUp();
diff --git a/tests/Integration/KoelPlus/Services/SongStorages/DropboxStorageTest.php b/tests/Integration/KoelPlus/Services/SongStorages/DropboxStorageTest.php
index e9314a62..f6a6272c 100644
--- a/tests/Integration/KoelPlus/Services/SongStorages/DropboxStorageTest.php
+++ b/tests/Integration/KoelPlus/Services/SongStorages/DropboxStorageTest.php
@@ -40,7 +40,7 @@ class DropboxStorageTest extends PlusTestCase
         $this->client = $this->mock(Client::class);
         $this->filesystem = $this->mock(DropboxFilesystem::class);
 
-        $this->filesystem->allows('getAdapter')->andReturns(
+        $this->filesystem->allows('getAdapter')->andReturn(
             Mockery::mock(DropboxAdapter::class, ['getClient' => $this->client])
         );