Throw ArgumentException If Charset Is Invalid
description
For a html page like below. charset is empty or invalid string
<html>
...
<head>
<meta http-equiv="Content-Type" content="text/html; charset=">
</head>
...
</html>
Parsing of the document would throw a ArgumentException. This is not user-friendly. It is preferable to have HtmlAgility ignore invalid charset value.
Root cause is in file HtmlDocument.cs, function ReadDocumentEncoding, Encoding.GetEncoding(charset) throws a ArgumentException if the argument is not invalid charset name.