title: Angular/fire Cannot read properties of undefined (reading 'FIREBASE_DATABASE_EMULATOR_HOST')
body: <p>I keep getting this error using angular/fire and firebase but can't find a solution in the web.</p>
  <p>It happens only when I import <strong>AngularFireDatabase</strong> like this:</p>
  <pre><code>import { AngularFireDatabase } from '@angular/fire/compat/database';
  ...
   constructor(public angularDb: AngularFireDatabase,    
      private afAuth: AngularFireAuth) {    }
  </code></pre>
  <p><strong>AngularFireAuth</strong> works.</p>
  <p>I already have the database enabled for testing purposes and I am using the latest versions:</p>
  <pre><code>&quot;@angular/fire&quot;: &quot;^7.2.0&quot;,
  &quot;firebase&quot;: &quot;^9.5.0&quot;,
  </code></pre>
  <p>I tried removing all node_modules and cache and installing again but it didn't work.</p>
  <p>I also tried using previous packages versions but got same error.</p>
  <p>Full error message:
  <a href="https://i.stack.imgur.com/DcjDM.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/DcjDM.png" alt="AngularFireDatabase" /></a></p>