title: Node.js and eslint disagree on "use strict"
body: <p>ESLint tells me that I do not need <code>"use strict"</code> at the top of my index.js file (it's a simple server like the 6-line one on <a href="https://nodejs.org/en/about/" rel="noreferrer">https://nodejs.org/en/about/</a>). Apparently all node modules are already in strict mode. Makes sense. </p>
  
  <p>However, running <code>node index.js</code> gets me a "SyntaxError: [let] not supported outside strict mode." <em>does</em> run with the "redundant" <code>"use strict"</code> pragma. </p>
  
  <p>Why the inconsistency? Shouldn't node know that this node module is indeed strict by default? Could this be due to some simple misconfiguration of node, ESLint, or my IDE? </p>