showReward method Null safety

Implementation

static Future<bool> showReward() async {
  if (kIsWeb) {
    AdsenseAdsView.showInter();
  }

  /// use this to check if user was rewarded
  bool anser = false;

  await RewardedAd.load(
    adUnitId: "ca-app-pub-8286573828419993/5994759567",
    request: const AdRequest(),
    rewardedAdLoadCallback: RewardedAdLoadCallback(
      onAdLoaded: (RewardedAd rewAd) {
        log('$rewAd loaded.');
        // Keep a reference to the ad so you can show it later.

        rewAd.fullScreenContentCallback = FullScreenContentCallback(
          onAdShowedFullScreenContent: (RewardedAd ad) =>
              log('$ad onAdShowedFullScreenContent.'),
          onAdDismissedFullScreenContent: (RewardedAd ad) {
            log('$ad onAdDismissedFullScreenContent.');
            ad.dispose();
          },
          onAdFailedToShowFullScreenContent: (RewardedAd ad, AdError error) {
            log('$ad onAdFailedToShowFullScreenContent: $error');
            ad.dispose();
          },
          onAdImpression: (RewardedAd ad) => log('$ad impression occurred.'),
        );

        rewAd.show(
          onUserEarnedReward: (
            AdWithoutView ad,
            RewardItem rewardItem,
          ) {
            // Reward the user for watching an ad.
            FirebaseAnalytics.instance.logEarnVirtualCurrency(
              virtualCurrencyName: rewardItem.type,
              value: rewardItem.amount,
            );

            anser = true;
          },
        );
      },
      onAdFailedToLoad: (LoadAdError error) {
        log('RewardedAd failed to load: $error');
      },
    ),
  );

  return anser;
}