Check if continuation is active

app/src/googleplay/java/org/tasks/billing/BillingClientImpl.kt

@@ -150,11 +150,14 @@ class BillingClientImpl(
                                 cont.resumeWith(Result.success(result))
                             }
                         } else {
+                            connected = false
+                            if (cont.isActive) {
                                 cont.resumeWithException(
                                     IllegalStateException(result.responseCodeString)
                                 )
                             }
                         }
+                    }
 
                     override fun onBillingServiceDisconnected() {
                         Timber.d("onBillingServiceDisconnected()")