Form builder - trying to create/edit relationship with pivot

public function events()
    {
        return $this->belongsToMany(MusicEvent::class,'music_event_artist','artist_id','music_event_id')
            ->withPivot("id","artist_id","music_event_id")
            ->using(EventArtist::class);
    }

public function artists()
    {
        return $this->belongsToMany(Artist::class,'music_event_artist','music_event_id','artist_id')
            ->withPivot("id","artist_id","music_event_id")
            ->using(EventArtist::class);
    }

class EventArtist extends Pivot
{
    public $table = "music_event_artist";
    protected $fillable = ['artist_id','music_event_id'];
}

protected static string $relationship = 'artists';
        return $form
            ->schema([
                Forms\Components\Select::make('artists')
                    ->label('Event Artist')
                    ->options(Artist::orderBy('name')->get()->pluck('name','id'))
                    ->searchable(),
        ]);

Duplicate entry '' for key 'code'
insert into 

 () values ()

$e = MusicEvent::find(1234);

= App\Models\MusicEvent {#7128
    id: 1234,
    description: "Test data here",
    artists: Collection {#7106
      all: [
        App\Models\Artist (etc),
        pivot: App\Models\EventArtist...
        },
      ],
    },
  }
  
$e2 = Artist::find($e->artists[0]->id);
= App\Models\Artist {#7108
    id: 6789,
    code: "jado",
    name: "Jane Doe",
  }