title: Ionic cordova resources --splash and --icon error
body: <p>I´m getting this error on resources generator:<br>
  <code>Error: end() has already been called, so it's too late to start piping</code></p>
  
  <p>I´m stuck with this error. Shows up when I try to generate resources:</p>
  
  <pre><code>PS F:\Desenvolvimento\Ionic\Divas&gt; ionic cordova resources ios -f
  √ Collecting resource configuration and source images - done!
  √ Filtering out image resources that do not need regeneration - done!
  √ Uploading source images to prepare for transformations: 2 / 2 complete - done!
  - Generating platform resources: 8 / 32 complete
  C:\Users\Gustavo\AppData\Roaming\npm\node_modules\ionic\node_modules\superagent\lib\node\index.js:859
        throw Error("end() has already been called, so it's too late to start piping");
        ^
  
  Error: end() has already been called, so it's too late to start piping
      at Response.response.pipe (C:\Users\Gustavo\AppData\Roaming\npm\node_modules\ionic\node_modules\superagent\lib\node\index.js:859:13)
      at Request.req.type.send.on.res (C:\Users\Gustavo\AppData\Roaming\npm\node_modules\ionic\lib\integrations\cordova\resources.js:166:25)
      at Request.emit (events.js:182:13)
      at Request._emitResponse (C:\Users\Gustavo\AppData\Roaming\npm\node_modules\ionic\node_modules\superagent\lib\node\index.js:862:8)
      at ClientRequest.req.once.res (C:\Users\Gustavo\AppData\Roaming\npm\node_modules\ionic\node_modules\superagent\lib\node\index.js:412:10)
      at Object.onceWrapper (events.js:273:13)
      at ClientRequest.emit (events.js:187:15)
      at HTTPParser.parserOnIncomingClient [as onIncoming] (_http_client.js:556:21)
      at HTTPParser.parserOnHeadersComplete (_http_common.js:109:17)
      at TLSSocket.socketOnData (_http_client.js:442:20)
  </code></pre>
  
  <p>My system:</p>
  
  <pre><code>Ionic:
  
     ionic (Ionic CLI)  : 4.7.1 (C:\Users\Gustavo\AppData\Roaming\npm\node_modules\ionic)
     Ionic Framework    : ionic-angular 3.9.2
     @ionic/app-scripts : 3.2.0
  
  Cordova:
  
     cordova (Cordova CLI) : not installed
     Cordova Platforms     : android 6.3.0
     Cordova Plugins       : cordova-plugin-ionic-webview 1.1.1, (and 8 other plugins)
  
  System:
  
     NodeJS : v10.15.0 (C:\Program Files\nodejs\node.exe)
     npm    : 6.5.0
     OS     : Windows 10
  </code></pre>