What is an unhandled promise rejection?
<p>For learning Angular 2, I am trying their tutorial. </p>

<p>I am getting an error like this:</p>

<pre><code>(node:4796) UnhandledPromiseRejectionWarning: Unhandled promise rejection (r                                                                                                     ejection id: 1): Error: spawn cmd ENOENT
[1] (node:4796) DeprecationWarning: Unhandled promise rejections are deprecated.
In the future, promise rejections that are not handled will terminate the Node.
js process with a non-zero exit code.
</code></pre>

<p>I went through different questions and answers in SO but could not find out what an "Unhandled Promise Rejection" is.</p>

<p>Can anyone simply explain me what it is and also what <code>Error: spawn cmd ENOENT</code> is, when it arises and what I have to check to get rid of this warning?</p>