title: Flutter In App Purchases Consumable Product - Purchase Stream not firing
body: <p>I am using in_app_purchases flutter package to handle my in app purchasing needs on both android and ios. I only use consumable IAP. But my purchase stream is not firing. Only the queryPastPurchases method returns the list of the consumable. So Im bit confused with the plugin. I have also started to listen to the purchasestream as soon as the app starts in the main method. However Im not receiving the purchase updates in the Purchase Stream.</p>
  <p>Also this statement from the in_app_purchase seems a bit ambigous it says trying to complete a pending purchase can cause a error. However it is mentioned to retry the purchase completion on pending status</p>
  <pre><code>Completing a [PurchaseStatus.pending] purchase will cause an exception.
  For convenience, [PurchaseDetails.pendingCompletePurchase] indicates if a 
  purchase is pending for completion.
  
  The method returns a [BillingResultWrapper] to indicate a detailed status 
  of the complete process.
  If the result contains [BillingResponse.error] or 
  [BillingResponse.serviceUnavailable], the developer should try
  to complete the purchase via this method again, or retry the 
  [completePurchase] it at a later time.
  If the result indicates other errors, there might be some issue with
  the app's code. The developer is responsible to fix the issue.
  </code></pre>