arangojs: Sporadic cursor not found error (1600 error code)

I have a troublesome issue where i’m sporadicly getting the dreaded cursor not found error. What i’ve tracked down is that it only seems to happen on queries that return more than 1K records.

Here’s the error i’m getting:

{ ArangoError: cursor not found
     at new ArangoError (/usr/src/app/node_modules/arangojs/lib/async/error.js:71:21)
     at Object.resolve (/usr/src/app/node_modules/arangojs/lib/async/connection.js:243:32)
     at _hosts.(anonymous function) (/usr/src/app/node_modules/arangojs/lib/async/connection.js:122:26)
     at IncomingMessage.res.on (/usr/src/app/node_modules/arangojs/lib/async/util/request.node.js:48:21)
     at IncomingMessage.emit (events.js:185:15)
     at endReadableNT (_stream_readable.js:1106:12)
     at process._tickCallback (internal/process/next_tick.js:178:19)
   isArangoError: true,
...

Here’s the relevant code which sporadically causes this error:

console.log('query = ', query)
  db.query(query)
    .then(cursor => {
      // console.log('cursor = ', cursor)
      return cursor.each(result => {
        if (result !== null && result.resourceType !== 'Statement' && result.resourceType !== 'StatementGroup') {
          results.push(result)
          auditRead(req, result)
            .then(() => {
              return Promise.resolve()
            })
            .catch(err => {
              return Promise.reject()
            })
        }
      })
    })
    .then(() => {
      results = Bundle.wrapInBundle(ReqHelpers.getBaseUrl(req), results, BundleType.searchSet)
      results = FhirHelpers.stripArangoAttributesFromBundle(results)
      return res.status(HttpStatus.OK).send(results)
    })
    .catch(err => {
      console.error('err in $everyting catch = ', err)
      if (err.isArangoError) {
        let response = FhirHelpers.generateErrorObject(IssueType.exception, req.path, err.response.body.errorMessage)
        return res.status(err.response.statusCode).send(response)
      } else {
        let response = FhirHelpers.generateErrorObject(IssueType.exception, req.path)
        return res.status(HttpStatus.INTERNAL_SERVER_ERROR).send(response)
      }
    })
}

/**
 * Save audit information for a read
 * @param  {Object} req       The request object
 * @param  {Array}  resources array of resources
 * @return {[type]} [description]
 */
function auditRead (req, resources) {
  return new Promise((resolve, reject) => {
    let event = FhirHelpers.generateAuditEvent(req, FhirHelpers.typeOfAction().read)

    const auditEvents = db.collection('auditevents')
    const auditEdges = db.collection('auditedges')

    auditEvents.save(event)
      .then(info => {
        // If it's an array, save every record as an auditevent, else save the single record as an auditevent
        if (Array.isArray(resources.entry)) {
          for (let resource of resources.entry) {
            let eventEdge = {
              _key: uuidv4(),
              _from: info._id,
              _to: 'clindocs/' + resource.resourceType + '$' + resource.id 
            }
            auditEdges.save(eventEdge)
              .then(edgeInfo => {
                return Promise.resolve()
              })
              .catch(err => {
                return Promise.reject(err)
              })
          }
        }

        return Promise.resolve()
      })
      .catch(err => {
        return Promise.reject(err)
      })
  })
}

I’m using arangojs version 6.6.0