title: Angular 7: params.map is not a function
body: <p>On trying to run my Angular 7 app using <code>ng serve</code>, I have suddenly been receiving the following error:</p>
  
  <p><code>ERROR in params.map is not a function</code></p>
  
  <p>I have no idea where this error is coming from and ng is not giving away too many details.</p>
  
  <p>I have tried reinstalling node, running <code>npm cache clean --force</code>. I have also tried reverting to a previous commit, which makes me think it is a problem with npm and not my code.</p>
  
  <p>Anyone seen this before?  A Google search yields only meagre results.</p>