title: How to catch Client is Offline error in Flutter Firebase Firestore
body: <p>I have been working with Firestore and am successful in implementing it. However, when I test it offline, aiming to implement a respective UI display that there is no access to the server at that time or anything, I keep getting a <strong>the client is offline</strong> error and for some reason, there's no way for me to catch it.</p>
  <p>Here's the error message:</p>
  <pre><code>Exception has occurred.
  PlatformException (PlatformException(Error performing get, Failed to get document because the client is offline., null))
  </code></pre>
  <p>Here's also my sample code:</p>
  <pre><code>DocumentReference ref = firestoreDb.collection('collection').document('doc1');
  
  try{
      ref.get().then((DocumentSnapshot ds){
          if(ds.exists == true){
              print('ds exists');
          }else{
              print('ds does not exist);
          }
      }).catchError((err){
          print(err);
      });
  } on PlatformException catch (err){
      print(err);
  } catch (err){
      print(err);
  }
  </code></pre>
  <p>Any of the error catches in the sample code we're bypassed and the error is not actually caught. I need to atleast catch the <strong>client is offline</strong> exception so I can properly update my UI.</p>