title: Response header settings is not working for the error case
body: <p><strong>ctx.Response.Header.Set</strong> function is not working for the error case.</p>
  <p>Please check the below code,</p>
  <pre><code>package main
  
  import &quot;fmt&quot;
  import &quot;github.com/valyala/fasthttp&quot;
  
  func main() {
      requestHandler := func(ctx *fasthttp.RequestCtx) {
          ctx.Response.Header.Set(&quot;Access-Control-Allow-Origin&quot;, &quot;*&quot;)
          switch string(ctx.Path()) {
          case &quot;/foo&quot;:
              fmt.Fprintf(ctx, &quot;Success result&quot;)
          case &quot;/bar&quot;:
              ctx.Error(&quot;Unsupported path&quot;, fasthttp.StatusNotFound)
          }
      }
      fasthttp.ListenAndServe(&quot;:8080&quot;, requestHandler)
  }
  </code></pre>
  <p>The /foo URL's response header is,</p>
  <blockquote>
  <p>Server: fasthttp Date: Mon, 16 Apr 2018 04:05:10 GMT</p>
  <p>Content-Type: text/plain; charset=utf-8</p>
  <p>Content-Length: 14</p>
  <p>Access-Control-Allow-Origin: *</p>
  </blockquote>
  <p>But, the /bar 's response header is,</p>
  <blockquote>
  <p>Server: fasthttp</p>
  <p>Date: Mon, 16 Apr 2018 04:05:50 GMT</p>
  <p>Content-Type: text/plain; charset=utf-8</p>
  <p>Content-Length: 16</p>
  </blockquote>
  <p>Access-Control-Allow-Origin header is not applied. Is anything I missed here?</p>