Given example throws exception

[graemejob]

RoslynPad code:

#r "nuget: ExpressionDelegates.Base, 1.0.0"
using ExpressionDelegates;
using System.Linq;
using System.Linq.Expressions;

Expression<Func<string, int>> expression = s => s.Length;
MemberInfo accessorInfo = ((MemberExpression)expression.Body).Member;

Accessor lengthAccessor = ExpressionDelegates.Accessors.Find(accessorInfo);

**var value = lengthAccessor.Get("17 letters string");** 

ExpressionDelegates.Accessors.Find returns null, so .Get causes a null reference exception.