MaxListenersExceededWarning on nodejs@10.1

[tylerbrandt]

Since nodejs@10.1, the test suite (npm run test-travis) has started emitting thousands of instances of:

(node:2877) MaxListenersExceededWarning: Possible EventEmitter memory leak detected. 2 error listeners added. Use emitter.setMaxListeners() to increase limit

I am not sure if this is indicative of a real regression in nodejs production usage, but it is definitely breaking the build (https://travis-ci.org/optimizely/javascript-sdk/jobs/381767712), and can be reproduced on my Mac using nvm install 10.1.

This wasn't/isn't an issue on nodejs@10.0 (https://travis-ci.org/optimizely/javascript-sdk/jobs/376595175)

[mikeproeng37]

Tested on one of our demo apps with @optimizely/optimizely-sdk@2.0.1 running on Node 10.1 and called some of the APIs: activate and getFeatureVariableBoolean. Everything seems to be working normally. Will look into whether it is a symptom in our test suite with mocha.

[mikeproeng37]

Ran npm test within packages/optimizely-sdk to completion with all tests passing. Looks like issue might be stemming from our use of Lerna at the top level repo to run tests across all packages

[aliabbasrizvi]

@mikeng13 may be good to look at why tests are failing on @tylerbrandt 's system

[spencerwilson-optimizely]

Recent tests against the current v10 release don't seem to exhibit this issue (example). Will close this, but please reopen if you observe the issue again!