Custom Logging in a transaction

create table #log_temp (msg varchar(255)) --main log tbl
declare @t table (msg varchar(255)) --our backup log
create table  #t (i int)
begin tran
begin try
insert #t values (1)
insert #log_temp values ( 'first')
insert @t values('first')

                insert #t values (2)
insert #log_temp values ( 'second')
insert @t values('second')

insert #t values (3)
insert #log_temp values ( 'third')
insert @t values('third')

insert #t values (4)
insert #log_temp values ('fourth')
insert @t values('fourth')

insert #t values (5)
insert #log_temp values ('fifth')
insert @t values('fifth')

insert #t values ('v') --introduce a runtime error
insert #log_temp values ('sixth')
insert @t values('sixth')

insert #t values (7)
insert #log_temp values ('seventh')
insert @t values('seventh')

insert #t values (8)
insert #log_temp values ('eighth')
insert @t values('eighth')
end try
begin catch
select * from #t -- data still there
rollback tran --clears everything including log_temp
                                select * from #log_temp --log is gone
                                select * from #t -- data is gone
insert #log_temp select * from @t --backfill the log 
insert #log_temp values('Rollback: '+error_message()) --insert the reason for rollback
end catch
if @@trancount>0
commit tran

drop table #t

select * from #log_temp -- log is back including the last error
drop table #log_temp