Unfriendly error message for builtin reduce function _stats

Items ~ 5M.

Query (with negative connection timeout) :-
http://10.2.1.64:8092/default/_design/dev_temp/_view/temp?stale=false&connection_timeout=-1&limit=10&skip=0

Design doc:-
{"_id":"_design/dev_temp","_rev":"4-a2116f64","views":{"temp":{"map":"function (doc)

{\n emit(doc._id, [doc.achievements, doc.coins]);\n}

","reduce":"_stats"}}}

Error:-

"from": "local",
"reason": "{function_clause,\n [

{couch_query_servers,builtin_stats,\n [reduce,\n [[[<<\"01b7575c38dac42f\">>,<<\"01b7575c38dac42f\">>],[\"\\r%m�-I\",4.39]],\n [[<<\"02c29fad5f164d62\">>,<<\"02c29fad5f164d62\">>],\n [[3,94,134,62,146,176],7.06]],\n [[<<\"039b9f5c48fb1bbe\">>,<<\"039b9f5c48fb1bbe\">>],[\"Oo�m\",9.23]],\n [[<<\"06866f020cb80790\">>,<<\"06866f020cb80790\">>],[\"=�\",16.7]],\n [[<<\"07b1e246e902a97f\">>,<<\"07b1e246e902a97f\">>],\n [[76,157,157,179,14,239],19.69]],\n [[<<\"094bc4aa468a6cb4\">>,<<\"094bc4aa468a6cb4\">>],\n [[48,80,134,214,52,206],23.79]],\n [[<<\"0a1e1d8da51f5dd7\">>,<<\"0a1e1d8da51f5dd7\">>],\n [[62,142,187,197,91],25.9]],\n [[<<\"0a797fd202caabdf\">>,<<\"0a797fd202caabdf\">>],[\" ..@�9�\",26.81]],\n [[<<\"0a862b7f915e2f79\">>,<<\"0a862b7f915e2f79\">>],\n [[54,126,135,185,58,156],26.94]],\n [[<<\"0ac60fb446a982fc\">>,<<\"0ac60fb446a982fc\">>],\n [[21,53,107,207,138],27.58]],\n [[<<\"0b0b963ba25b9d38\">>,<<\"0b0b963ba25b9d38\">>],\n [[5,85,103,153,51,93,213],28.27]],\n [[<<\"0b96459020caf4e1\">>,<<\"0b96459020caf4e1\">>],\n [[78,188,116,131],29.66]]]]}

,\n

{couch_query_servers,builtin_reduce,4}

,\n

{couch_query_servers,reduce,3}

,\n

{couch_view_group,'-init_group/4-fun-1-',4}

,\n

{couch_btree,'-write_node/3-lc$^0/1-0-',5}

,\n

{couch_btree,write_node,3}

,\n

{couch_btree,modify_node,8}

,\n

{couch_btree,query_modify,6}

]}"
}

Attaching the diags