c# SyntaxFactory.ParseAttributeArgumentList throws NullReferenceException with invalid string

[AdmiralSnyder]

Version Used:
typeof(SyntaxFactory).Assembly.ImageRuntimeVersion = v4.0.30319

Steps to Reproduce:
in c# interactive:

1. #r "Microsoft.CodeAnalysis.CSharp.dll"
2. using Microsoft.CodeAnalysis.CSharp;
3. SyntaxFactory.ParseAttributeArgumentList("somethingWithoutBrackets")
4. Then this exception is being thrown:
   Object reference not set to an instance of an object.

• Microsoft.CodeAnalysis.CSharp.Syntax.InternalSyntax.SyntaxParser.AddError(TNode, Microsoft.CodeAnalysis.CSharp.ErrorCode, object[])
• Microsoft.CodeAnalysis.CSharp.Syntax.InternalSyntax.LanguageParser.ConsumeUnexpectedTokens(TNode)
• Microsoft.CodeAnalysis.CSharp.SyntaxFactory.ParseAttributeArgumentList(string, int, Microsoft.CodeAnalysis.ParseOptions, bool)

Expected Behavior:
some kind of ParseException, e.g. UnexpectedTokenException
Actual Behavior:
NullReferenceException with stacktrace.