TypeError: Cannot read property 'docType' of undefined about cozy-data-system

[nono]

I think I got the same by running the integration tests from cozy-desktop:

[2016-06-16 16:05:03:388] error - helper/db_feed | CouchError: not_found: deleted
    at Request._onResponse [as _callback] (/usr/local/cozy/apps/data-system/node_modules/cradle/lib/cradle.js:241:29)
    at Request.self.callback (/usr/local/cozy/apps/data-system/node_modules/request/request.js:198:22)
    at emitTwo (events.js:87:13)
    at Request.emit (events.js:172:7)
    at Request.<anonymous> (/usr/local/cozy/apps/data-system/node_modules/request/request.js:1035:10)
    at emitOne (events.js:82:20)
    at Request.emit (events.js:169:7)
    at IncomingMessage.<anonymous> (/usr/local/cozy/apps/data-system/node_modules/request/request.js:962:12)
    at emitNone (events.js:72:20)
    at IncomingMessage.emit (events.js:166:7)
[2016-06-16 16:05:03:388] error - helper/db_feed | CouchError: not_found: deleted
    at Request._onResponse [as _callback] (/usr/local/cozy/apps/data-system/node_modules/cradle/lib/cradle.js:241:29)
    at Request.self.callback (/usr/local/cozy/apps/data-system/node_modules/request/request.js:198:22)
    at emitTwo (events.js:87:13)
    at Request.emit (events.js:172:7)
    at Request.<anonymous> (/usr/local/cozy/apps/data-system/node_modules/request/request.js:1035:10)
    at emitOne (events.js:82:20)
    at Request.emit (events.js:169:7)
    at IncomingMessage.<anonymous> (/usr/local/cozy/apps/data-system/node_modules/request/request.js:962:12)
    at emitNone (events.js:72:20)
    at IncomingMessage.emit (events.js:166:7)
/usr/local/cozy/apps/data-system/build/server/lib/indexer.js:176
  docType = (ref = doc.docType) != null ? typeof ref.toLowerCase === "function" ? ref.toLowerCase() : void 0 : void 0;
                      ^

TypeError: Cannot read property 'docType' of undefined
    at Object.exports.onDocumentUpdate (/usr/local/cozy/apps/data-system/build/server/lib/indexer.js:176:23)
    at Object.callback (/usr/local/cozy/apps/data-system/build/server/lib/feed.js:188:19)
    at /usr/local/cozy/apps/data-system/node_modules/cradle/lib/cradle/database/documents.js:52:18
    at Request._onResponse [as _callback] (/usr/local/cozy/apps/data-system/node_modules/cradle/lib/cradle.js:241:20)
    at Request.self.callback (/usr/local/cozy/apps/data-system/node_modules/request/request.js:198:22)
    at emitTwo (events.js:87:13)
    at Request.emit (events.js:172:7)
    at Request.<anonymous> (/usr/local/cozy/apps/data-system/node_modules/request/request.js:1035:10)
    at emitOne (events.js:82:20)
    at Request.emit (events.js:169:7)