Bug: DecisionLog has updates even if there is no user action

[xinbenlv]

Error:

[info] PERF       193ms  500 POST /api/decisionLog/article ga_id=GA1.1.1534792152.1585848446 session_id=NCZrUBpjvATJqihb2N76EVwCEkBHdrM_
MongoError: E11000 duplicate key error collection: heroku_2dmqvqnm.DecisionLog index: user_id_1_title_1_timestamp_-1_type_1 dup key: { user_id: null, title: "Robert Adams (spiritual teacher)", timestamp: new Date(1597097003000), type: "articleLogEvent" }
    at Function.create (/Users/zzn/ws/wikiloop-doublecheck/node_modules/mongoose/node_modules/mongodb/lib/core/error.js:44:12)
    at toError (/Users/zzn/ws/wikiloop-doublecheck/node_modules/mongoose/node_modules/mongodb/lib/utils.js:150:22)
    at /Users/zzn/ws/wikiloop-doublecheck/node_modules/mongoose/node_modules/mongodb/lib/operations/common_functions.js:266:39
    at handler (/Users/zzn/ws/wikiloop-doublecheck/node_modules/mongoose/node_modules/mongodb/lib/core/sdam/topology.js:971:24)
    at /Users/zzn/ws/wikiloop-doublecheck/node_modules/mongoose/node_modules/mongodb/lib/core/sdam/server.js:496:5
    at /Users/zzn/ws/wikiloop-doublecheck/node_modules/mongoose/node_modules/mongodb/lib/core/connection/pool.js:414:18
    at processTicksAndRejections (internal/process/task_queues.js:79:11)
^C%