title: How to fix AssertionError [ERR_ASSERTION]: false == true?
body: <p>I'am using an relative old angular version app:</p>
  
  <pre><code>Angular CLI: 1.7.4
  Node: 8.11.1
  OS: darwin x64
  Angular: 5.2.10
  ... animations, common, compiler, compiler-cli, core, forms
  ... http, language-service, platform-browser
  ... platform-browser-dynamic, router
  
  @angular/cdk: 5.2.5
  @angular/cli: 1.7.4
  @angular/material-moment-adapter: 6.4.2
  @angular/material: 5.2.5
  @angular-devkit/build-optimizer: 0.3.2
  @angular-devkit/core: 0.3.2
  @angular-devkit/schematics: 0.3.2
  @ngtools/json-schema: 1.2.0
  @ngtools/webpack: 1.10.2
  @schematics/angular: 0.3.2
  @schematics/package-update: 0.3.2
  typescript: 2.4.2
  webpack: 3.11.0
  </code></pre>
  
  <p>The app runs fine and but time to time it just quit and throws the following error on the console:</p>
  
  <blockquote>
    <p>AssertionError [ERR_ASSERTION]: false == true
        at PriorityNode.removeChild (/Users/xxxx/yyyy/node_modules/spdy-transport/lib/spdy-transport/priority.js:74:3)
        at PriorityNode.remove (/Users/xxxx/yyyy/node_modules/spdy-transport/lib/spdy-transport/priority.js:62:15)
        at PriorityTree.add (/Users/xxxx/yyyy/node_modules/spdy-transport/lib/spdy-transport/priority.js:163:23)
        at Stream._initPriority (/Users/xxxx/yyyy/node_modules/spdy-transport/lib/spdy-transport/stream.js:101:25)
        at new Stream (/Users/xxxx/yyyy/node_modules/spdy-transport/lib/spdy-transport/stream.js:76:8)
        at Connection._createStream (/Users/xxxx/yyyy/node_modules/spdy-transport/lib/spdy-transport/connection.js:388:16)
        at Connection._handleHeaders (/Users/xxxx/yyyy/node_modules/spdy-transport/lib/spdy-transport/connection.js:436:21)
        at Connection._handleFrame (/Users/xxxx/yyyy/node_modules/spdy-transport/lib/spdy-transport/connection.js:319:10)
        at Parser. (/Users/xxxx/yyyy/node_modules/spdy-transport/lib/spdy-transport/connection.js:156:10)
        at emitOne (events.js:116:13)
        at Parser.emit (events.js:211:7)
        at addChunk (/Users/xxxx/yyyy/node_modules/readable-stream/lib/_stream_readable.js:284:12)
        at readableAddChunk (/Users/xxxx/yyyy/node_modules/readable-stream/lib/_stream_readable.js:271:11)
        at Parser.Readable.push (/Users/xxxx/yyyy/node_modules/readable-stream/lib/_stream_readable.js:238:10)
        at Parser.Transform.push (/Users/xxxx/yyyy/node_modules/readable-stream/lib/_stream_transform.js:146:32)
        at next (/Users/xxxx/yyyy/node_modules/spdy-transport/lib/spdy-transport/protocol/base/parser.js:53:12)</p>
  </blockquote>
  
  <p>Have been searching and found <a href="https://github.com/spdy-http2/spdy-transport/pull/57" rel="nofollow noreferrer">this one</a>, but it looks a kind of different to my issue and none of the suggestions could give me the right fix.</p>
  
  <p>Any hint or idea how to fix this? I notice this error after I did implement an eventEmitter function to pass some data from child to parent component.
  Could this be the reason?</p>