fix Illegal callback invocation from native module crash (#347)

* fix Illegal callback invocation from native module. crash * remove newline

Author: candyan

android/src/main/java/com/sbugert/rnadmob/RNAdMobRewardedVideoAdModule.java

@@ -63,7 +63,10 @@ public void onRewarded(RewardItem rewardItem) {
  @Override
  public void onRewardedVideoAdLoaded() {
  sendEvent(EVENT_AD_LOADED, null);
- mRequestAdPromise.resolve(null);
+ if (mRequestAdPromise != null) {
+ mRequestAdPromise.resolve(null);
+ mRequestAdPromise = null;
+ }
  }
 
  @Override
@@ -117,7 +120,10 @@ public void onRewardedVideoAdFailedToLoad(int errorCode) {
  WritableMap error = Arguments.createMap();
  event.putString("message", errorMessage);
  sendEvent(EVENT_AD_FAILED_TO_LOAD, event);
- mRequestAdPromise.reject(errorString, errorMessage);
+ if (mRequestAdPromise != null) {
+ mRequestAdPromise.reject(errorString, errorMessage);
+ mRequestAdPromise = null;
+ }
  }
 
  private void sendEvent(String eventName, @Nullable WritableMap params) {