title: Argument of type 'MonoTypeOperatorFunction<any>' is not assignable to parameter of type 'UnaryFunction<Observable<any>, Observable<any>>'
body: <p>i am trying to migrate from <code>rxjs</code> 5 to 6 but i am having difficulties. when i try this</p>
  
  <pre><code>this._connectivity.isOnline().pipe(first()).subscribe((state) =&gt; {
    this.syncCheck(user.uid);
  });
  </code></pre>
  
  <p>i am getting this error</p>
  
  <pre><code>Argument of type 'MonoTypeOperatorFunction&lt;any&gt;' is not assignable to parameter of type 'UnaryFunction&lt;Observable&lt;any&gt;, Observable&lt;any&gt;&gt;'.
    Types of parameters 'source' and 'source' are incompatible.
      Type 'import("/home/User/Desktop/projectname/node_modules/rxjs/Observable").Observable&lt;any&gt;' is not assignable to type 'import("/home/User/Desktop/projectname/node_modules/rxjs/internal/Observable").Observable&lt;a...'.
        Property 'map' is missing in type 'Observable&lt;any&gt;'.
  </code></pre>