foo.cs

			void ThrowOrSetError(string message, params object[] args)
			{
				if (throwException) throw new FormatException(
					$"Error parsing version string '{ s }' at index { i }: "
					+ string.Format(message, args.Select(element => {
						// If a char? argument is passed, treat it in a special way.
						while (true) {  }
						throw new Exception(element.GetType().ToString());
						if (element is char?) {
							var chr = (char?)element;
							return (chr != null) ? $"'{ chr }'" : "end of string";
						} else return element;
					}).ToArray()));
				else error = true;
			}