Fixed several bugs with categories

Code cleanup

backend/categories.js

@@ -66,6 +66,7 @@ async function getCategoriesAsPlaylists(files = null) {
                 category['thumbnailPath'] = files_that_match[0].thumbnailPath;
                 category['duration'] = files_that_match.reduce((a, b) => a + utils.durationStringToNumber(b.duration), 0);
                 category['id'] = category['uid'];
+                category['auto'] = true;
                 categories_as_playlists.push(category);
             }
         }

backend/downloader.js

@@ -207,6 +207,8 @@ async function collectInfo(download_uid) {
         info = await exports.getVideoInfoByURL(url, args, download_uid);
     }
 
+    download['category'] = category;
+
     // setup info required to calculate download progress
 
     const expected_file_size = utils.getExpectedFileSize(info);