AsuraToon Crash on no Artists or Authors

Fix #296

Author: C9Glax

Tranga/MangaConnectors/AsuraToon.cs

@@ -102,11 +102,13 @@ private Manga ParseSinglePublicationFromHtml(HtmlDocument document, string publi
 
 		HtmlNode descriptionNode =
 			document.DocumentNode.SelectSingleNode("//h3[starts-with(text(),'Synopsis')]/../span");
-		string description = descriptionNode.InnerText;
+		string description = descriptionNode?.InnerText??"";
 
 		HtmlNodeCollection authorNodes = document.DocumentNode.SelectNodes("//h3[text()='Author']/../h3[not(text()='Author' or text()='_')]");
-		HtmlNodeCollection artistNodes = document.DocumentNode.SelectNodes("//h3[text()='Artist']/../h3[not(text()='Author' or text()='_')]");
-		List<string> authors = authorNodes.Select(a => a.InnerText).Concat(artistNodes.Select(a => a.InnerText)).ToList();
+		HtmlNodeCollection artistNodes = document.DocumentNode.SelectNodes("//h3[text()='Artist']/../h3[not(text()='Artist' or text()='_')]");
+		IEnumerable<string> authorNames = authorNodes is null ? [] : authorNodes.Select(a => a.InnerText);
+		IEnumerable<string> artistNames = artistNodes is null ? [] : artistNodes.Select(a => a.InnerText);
+		List<string> authors = authorNames.Concat(artistNames).ToList();
 
 		HtmlNode? firstChapterNode = document.DocumentNode.SelectSingleNode("//a[contains(@href, 'chapter/1')]/../following-sibling::h3");
 		int? year = int.Parse(firstChapterNode?.InnerText.Split(' ')[^1] ?? "2000");