WDIO Javascript Mocha/Chai crashes NPM when expect fails - webdriver-io

Question

When running a test, the it blocks are being executed and I'm getting this output.
What I am unable to understand is why the npm command is exiting with an error?
3) GAMETRIBE CELL C WAP DOI - SUCCESS FLOW Webdriver should target and click the subscription CTA:
An element could not be located on the page using the given search parameters ("[class='button']").
running phantomjs
Error: An element could not be located on the page using the given search parameters ("[class='button']").
at getText() - index.js:312:3
npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! webdriver_typescript#1.0.0 test-cellc: `node ./node_modules/typescript/lib/tsc.js && node ./node_modules/webdriverio/bin/wdio ./dist/wdio.conf.mcm.js --suite cellcWapDoi`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the webdriver_typescript#1.0.0 test-cellc script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.
npm ERR! A complete log of this run can be found in:
npm ERR! /Users/davidabes/.npm/_logs/2017-12-14T06_44_07_155Z-debug.log
My test cases look like this:
export default function() {
it('Webdriver should target and click the subscription CTA', function() {
const yesLink = browser.element("[class='button']");
console.log(yesLink.getText());
console.log(yesLink.getTagName());
yesLink.click();
});

Answer 1

It seems if any of the tests fail, then it seems mocha exits with an error code of 1 ... I just can't remember where in the docs I read this.