Fix json null string

app/src/main/java/org/koitharu/kotatsu/domain/local/MangaIndex.kt

@@ -7,6 +7,7 @@ import org.koitharu.kotatsu.core.model.Manga
 import org.koitharu.kotatsu.core.model.MangaChapter
 import org.koitharu.kotatsu.core.model.MangaSource
 import org.koitharu.kotatsu.core.model.MangaTag
+import org.koitharu.kotatsu.utils.ext.getStringOrNull
 import org.koitharu.kotatsu.utils.ext.map
 import org.koitharu.kotatsu.utils.ext.safe
 
@@ -44,12 +45,12 @@ class MangaIndex(source: String?) {
 		Manga(
 			id = json.getLong("id"),
 			title = json.getString("title"),
-			altTitle = json.getString("title_alt"),
+			altTitle = json.getStringOrNull("title_alt"),
 			url = json.getString("url"),
 			source = source,
 			rating = json.getDouble("rating").toFloat(),
 			coverUrl = json.getString("cover"),
-			description = json.getString("description"),
+			description = json.getStringOrNull("description"),
 			tags = json.getJSONArray("tags").map { x ->
 				MangaTag(
 					title = x.getString("title"),

app/src/main/java/org/koitharu/kotatsu/utils/ext/JsonExt.kt

@@ -21,4 +21,6 @@ fun <T> JSONArray.mapIndexed(block: (Int, JSONObject) -> T): List<T> {
 		result.add(block(i, jo))
 	}
 	return result
-}
+}
+
+fun JSONObject.getStringOrNull(name: String): String? = opt(name)?.toString()