Close all the service broker connections - tsql

Question

I'm trying to get all the conversation handlers to get closed, before killing the service broker.
I see that in the code above I cannot quite get the guid for conversation_handler (If I debug I see it has an empty value shown as {...}).
Furthermore, sometimes the ##ROWCOUNT returns 1 (even when the queried queue table is empty).
Am I missing something about how to retrieve output parameters using sp_executesql ?
set rowcount 1
--ITERATORS
declare #ServiceName varchar(100)
select #ServiceName = ServiceName from #services_and_queues
declare #QueueName varchar(100)
select #QueueName = QueueName from #services_and_queues
declare #IsMsShipped bit
select #IsMsShipped = IsMsShipped from #services_and_queues
while ##rowcount <> 0
begin
set rowcount 0
--SYSTEM QUEUES CANNOT BE CHANGED, NOR THE SERVICES ASSOCIATED WITH THEM
if( #IsMsShipped = 0)
BEGIN
--END ALL THE CONVERSATIONS FOR THE CURRENT QUEUE
declare #conversation_handler uniqueidentifier
while(1=1)
begin
DECLARE #SQL nvarchar(max) = N'select top 1 #conversation_handler = conversation_handle from ' + #QueueName
exec sp_executesql #SQL, N'#conversation_handler uniqueidentifier out', #conversation_handler out
if (##ROWCOUNT = 0 or #conversation_handler = null or trim(CAST(#conversation_handler AS char(36))) = '')
break
end conversation #conversation_handler with cleanup
end
END
delete #services_and_queues where ServiceName = #ServiceName
set rowcount 1
select #ServiceName = ServiceName from #services_and_queues
select #QueueName = QueueName from #services_and_queues
select #IsMsShipped = IsMsShipped from #services_and_queues
end
set rowcount 0
DROP TABLE #services_and_queues