packages/redux-saga/src/internal/proc.js
function currCb(res, isErr) {
      if (effectSettled) {
        return
      }

      effectSettled = true
      cb.cancel = noop // defensive measure
      if (sagaMonitor) {
        isErr ? sagaMonitor.effectRejected(effectId, res) : sagaMonitor.effectResolved(effectId, res)
      }
      cb(res, isErr)
    }
function currCb(res, isErr) {
      if (effectSettled) {
        return
      }

      effectSettled = true
      cb.cancel = noop // defensive measure
      if (sagaMonitor) {
        isErr ? sagaMonitor.effectRejected(effectId, res) : sagaMonitor.effectResolved(effectId, res)
      }
      cb(res, isErr)
    }
Completion callback passed to the appropriate effect runner