couchdb js view failure

[Sat, 02 Jan 2010 21:47:53 GMT] [error] [<0.757.0>] ** Generic server couch_query_servers terminating 
** Last message in was {'EXIT',<0.769.0>,
                           {{try_clause,
                                <<"Cannot encode 'undefined' value as JSON">>},
                            [{couch_query_servers,os_reduce,3},
                             {couch_query_servers,reduce,3},
                             {couch_view_group,'-init_group/4-fun-0-',4},
                             {couch_btree,'-write_node/3-lc$^0/1-0-',3},
                             {couch_btree,write_node,3},
                             {couch_btree,modify_node,4},
                             {couch_btree,query_modify,4},
                             {couch_btree,add_remove,3}]}}
** When Server state == {237599,241696,245793,249890}
** Reason for termination == 
** {{try_clause,<<"Cannot encode 'undefined' value as JSON">>},
    [{couch_query_servers,os_reduce,3},
     {couch_query_servers,reduce,3},
     {couch_view_group,'-init_group/4-fun-0-',4},
     {couch_btree,'-write_node/3-lc$^0/1-0-',3},
     {couch_btree,write_node,3},
     {couch_btree,modify_node,4},
     {couch_btree,query_modify,4},
     {couch_btree,add_remove,3}]}


[Sat, 02 Jan 2010 21:47:53 GMT] [error] [<0.757.0>] {error_report,<0.23.0>,
    {<0.757.0>,crash_report,
     [[{initial_call,{couch_query_servers,init,['Argument__1']}},
       {pid,<0.757.0>},
       {registered_name,couch_query_servers},
       {error_info,
           {exit,
               {{try_clause,<<"Cannot encode 'undefined' value as JSON">>},
                [{couch_query_servers,os_reduce,3},
                 {couch_query_servers,reduce,3},
                 {couch_view_group,'-init_group/4-fun-0-',4},
                 {couch_btree,'-write_node/3-lc$^0/1-0-',3},
                 {couch_btree,write_node,3},
                 {couch_btree,modify_node,4},
                 {couch_btree,query_modify,4},
                 {couch_btree,add_remove,3}]},
               [{gen_server,terminate,6},{proc_lib,init_p_do_apply,3}]}},
       {ancestors,[couch_secondary_services,couch_server_sup,<0.1.0>]},
       {messages,[]},
       {links,[<0.467.0>,<0.781.0>]},
       {dictionary,[]},
       {trap_exit,true},
       {status,running},
       {heap_size,987},
       {stack_size,24},
       {reductions,311}],
      [{neighbour,
           [{pid,<0.781.0>},
            {registered_name,[]},
            {initial_call,{couch_os_process,init,['Argument__1']}},
            {current_function,{gen_server,loop,6}},
            {ancestors,
                [couch_query_servers,couch_secondary_services,
                 couch_server_sup,<0.1.0>]},
            {messages,[]},
            {links,[<0.757.0>,#Port<0.1536>]},
            {dictionary,[]},
            {trap_exit,false},
            {status,waiting},
            {heap_size,4181},
            {stack_size,9},
            {reductions,2543}]}]]}}

[Sat, 02 Jan 2010 21:47:53 GMT] [error] [<0.467.0>] {error_report,<0.23.0>,
              {<0.467.0>,supervisor_report,
               [{supervisor,{local,couch_secondary_services}},
                {errorContext,child_terminated},
                {reason,{{try_clause,<<"Cannot encode 'undefined' value as JSON">>},
                         [{couch_query_servers,os_reduce,3},
                          {couch_query_servers,reduce,3},
                          {couch_view_group,'-init_group/4-fun-0-',4},
                          {couch_btree,'-write_node/3-lc$^0/1-0-',3},
                          {couch_btree,write_node,3},
                          {couch_btree,modify_node,4},
                          {couch_btree,query_modify,4},
                          {couch_btree,add_remove,3}]}},
                {offender,[{pid,<0.757.0>},
                           {name,query_servers},
                           {mfa,{couch_query_servers,start_link,[]}},
                           {restart_type,permanent},
                           {shutdown,brutal_kill},
                           {child_type,worker}]}]}}

[Sat, 02 Jan 2010 21:47:53 GMT] [error] [<0.686.0>] {error_report,<0.23.0>,
    {<0.686.0>,crash_report,
     [[{initial_call,{mochiweb_socket_server,acceptor_loop,['Argument__1']}},
       {pid,<0.686.0>},
       {registered_name,[]},
       {error_info,
           {error,badarg,
               [{erlang,list_to_binary,
                    [[{couch_query_servers,os_reduce,3},
                      {couch_query_servers,reduce,3},
                      {couch_view_group,'-init_group/4-fun-0-',4},
                      {couch_btree,'-write_node/3-lc$^0/1-0-',3},
                      {couch_btree,write_node,3},
                      {couch_btree,modify_node,4},
                      {couch_btree,query_modify,4},
                      {couch_btree,add_remove,3}]]},
                {couch_httpd,error_info,1},
                {couch_httpd,send_error,2},
                {couch_httpd,handle_request,5},
                {mochiweb_http,headers,5},
                {proc_lib,init_p_do_apply,3}]}},
       {ancestors,
           [couch_httpd,couch_secondary_services,couch_server_sup,<0.1.0>]},
       {messages,[]},
       {links,[<0.476.0>,#Port<0.1510>]},
       {dictionary,
           [{mochiweb_request_body,
                <<"{\"language\":\"javascript\",\"map\":\"function (doc) {\\n  emit(null,1);\\n}\",\"reduce\":\"function (k,v,rrp){\\n  sum(v);\\n}\"}">>},
            {mochiweb_request_qs,[{"limit","11"},{"group","true"}]},
            {mochiweb_request_recv,true},
            {jsonp,undefined}]},
       {trap_exit,false},
       {status,running},
       {heap_size,6765},
       {stack_size,24},
       {reductions,43530}],
      []]}}

[Sat, 02 Jan 2010 21:47:53 GMT] [error] [<0.476.0>] {error_report,<0.23.0>,
              {<0.476.0>,std_error,
               {mochiweb_socket_server,235,{child_error,badarg}}}}
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