Fix for double callback consume crash

[pavel-alexeichik]

This commit fixes #315
Previous pull request #379 fixed the issue just partially.
Here is the stack showing the case when the app crashes:

java.lang.RuntimeException: 
  at com.facebook.react.bridge.CallbackImpl.invoke (CallbackImpl.java:28)
  at com.facebook.react.bridge.PromiseImpl.reject (PromiseImpl.java:68)
  at com.facebook.react.bridge.PromiseImpl.reject (PromiseImpl.java:36)
  at com.dooboolab.RNIap.RNIapModule.rejectPromiseWithBillingError (RNIapModule.java:458)
  at com.dooboolab.RNIap.RNIapModule.access$300 (RNIapModule.java:46)
  at com.dooboolab.RNIap.RNIapModule$3.onBillingSetupFinished (RNIapModule.java:132)
  at com.android.billingclient.api.BillingClientImpl$BillingServiceConnection.onServiceConnected (BillingClientImpl.java:908)
 
  at android.app.LoadedApk$ServiceDispatcher.doConnected (LoadedApk.java:1839)
  at android.app.LoadedApk$ServiceDispatcher$RunConnection.run (LoadedApk.java:1871)
  at android.os.Handler.handleCallback (Handler.java:873)
  at android.os.Handler.dispatchMessage (Handler.java:99)
  at android.os.Looper.loop (Looper.java:214)
  at android.app.ActivityThread.main (ActivityThread.java:6981)
  at java.lang.reflect.Method.invoke (Native Method)
  at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run (RuntimeInit.java:493)
  at com.android.internal.os.ZygoteInit.main (ZygoteInit.java:1445)

[hyochan]

Approve this PR. Thank you for contribution.

[pavel-alexeichik]

@hyochan Thank you for this great module 👍