Get list of permisison for a SQL role
The script is missing a left join to sys.types to grab table type information, which also requires execute permissions to use (alternatively join sys.table_types, you'll get the same data). Try the following:

SELECT  DB_NAME() AS 'DBName' ,
    p.[name] AS 'PrincipalName' ,
    p.[type_desc] AS 'PrincipalType' ,
    p2.[name] AS 'GrantedBy' ,
    dbp.[permission_name] ,
    dbp.[state_desc] ,
    CASE WHEN [dbp].[class_desc] = 'DATABASE' THEN 'DATABASE'
         ELSE COALESCE(so.[name], t.name)
    END AS 'ObjectName' ,
    CASE WHEN [dbp].[class_desc] = 'DATABASE' THEN 'DATABASE'
         ELSE COALESCE(so.[type_desc], N'TYPE')
    END AS 'ObjectType' 
FROM    [sys].[database_permissions] dbp
        LEFT JOIN [sys].[all_objects] so ON dbp.[major_id] = so.[object_id]
        LEFT JOIN [sys].[database_principals] p ON dbp.[grantee_principal_id] = p.[principal_id]
        LEFT JOIN [sys].[database_principals] p2 ON dbp.[grantor_principal_id] = p2.[principal_id]
        LEFT JOIN [sys].[types] t ON dbp.major_id = t.user_type_id
WHERE   p.[name] = 'db_executor';