Once a promise `reject()` callback is called, a warning message *&quot;Uncaught (in promise)&quot;* appears in the Chrome console. I can&#39;t wrap my head around the reason behind it, nor how to get rid of it.

    var p = new Promise((resolve, reject) =&gt; {
      setTimeout(() =&gt; {
        var isItFulfilled = false
        isItFulfilled ? resolve(&#39;!Resolved&#39;) : reject(&#39;!Rejected&#39;)
      }, 1000)  
    })
    
    p.then(result =&gt; console.log(result))
    p.catch(error =&gt; console.log(error))

Warning:

![enter image description here][2]

**Edit:**

I found out that if the `onRejected` handler is not explicitly provided to the `.then(onResolved, onRejected)` method, JS will automatically provide an implicit one. It looks like this: `(err) =&gt; throw err`. The auto generated handler will throw in its turn.

Reference:

&gt; If IsCallable(*onRejected*)` is **false**, then  
&gt; &amp;nbsp; &amp;nbsp; &amp;nbsp;Let *onRejected* be &quot;**Thrower**&quot;. 

http://www.ecma-international.org/ecma-262/6.0/index.html#sec-performpromisethen


  [1]: https://i.stack.imgur.com/H4GW7.jpg
  [2]: https://i.stack.imgur.com/fB3nJ.png

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Promise reject() causes "Uncaught (in promise)" warning