[MangaDex] Speed up large chapters list loading (hotfix)

src/main/kotlin/org/koitharu/kotatsu/parsers/site/MangaDexParser.kt

@@ -247,7 +247,7 @@ internal class MangaDexParser(override val context: MangaLoaderContext) : MangaP
 		val json = context.httpGet(url).parseJson()
 		if (json.getString("result") == "ok") {
 			return Chapters(
-				data = json.optJSONArray("data")?.filterIsInstance<JSONObject>().orEmpty(),
+				data = json.optJSONArray("data")?.toJSONList().orEmpty(),
 				total = json.getInt("total"),
 			)
 		} else {

src/main/kotlin/org/koitharu/kotatsu/parsers/util/json/JsonExt.kt

@@ -137,3 +137,7 @@ fun JSONArray?.isNullOrEmpty(): Boolean {
 
 	return this == null || this.length() == 0
 }
+
+fun JSONArray.toJSONList(): List<JSONObject> {
+	return List(length()) { i -> getJSONObject(i) }
+}