Slightly improved error message for when we can't find a proper constructor.

Dapper/SqlMapper.cs

@@ -1540,7 +1540,7 @@ static List<FieldInfo> GetSettableFields(Type t)
                 }
                 if (!hasDefaultConstructor && specializedConstructor == null)
                 {
-                    throw new InvalidOperationException("A parameterless default constructor or one matching order, names and types of values returned by the query is required to allow for dapper materialization");
+                    throw new InvalidOperationException(String.Format("Cannot find constructor for type {0}. A parameterless default constructor or one matching order, names and types of values returned by the query is required to allow for dapper materialization", type.FullName));
                 }
             }
             il.BeginExceptionBlock();