fix(plex): do not fail to scan empty libraries (#1771)

* fix(plex): do not fail to scan empty libraries

* fix(plex): ensure getLibraryContents returns array

server/api/plexapi.ts

@@ -142,7 +142,7 @@ class PlexAPI {
       `/library/sections/${id}/all`
     );
 
-    return response.MediaContainer.Metadata;
+    return response.MediaContainer.Metadata ?? [];
   }
 
   public async getMetadata(

server/lib/scanners/plex/index.ts

@@ -7,9 +7,9 @@ import { User } from '../../../entity/User';
 import { getSettings, Library } from '../../settings';
 import BaseScanner, {
   MediaIds,
+  ProcessableSeason,
   RunnableScanner,
   StatusBase,
-  ProcessableSeason,
 } from '../baseScanner';
 
 const imdbRegex = new RegExp(/imdb:\/\/(tt[0-9]+)/);