Handling IllegalStateException when loading or creating interstitial ads.

(reported in #121

New error code and message for the default fallback case in switch statements- ConstantsHelper.CALLBACK_ERROR_UNKOWN and ConstantsHelper.CALLBACK_ERROR_MESSAGE_UNKNOWN.
Corresponding new error code added to C++ side (admob/types.h)

Removed a redundant overridden method as it was just calling its base class method directly.

Updated release notes with this bugfix

PiperOrigin-RevId: 333125360

Author: Googler

admob/src/include/firebase/admob/types.h

@@ -72,6 +72,8 @@ enum AdMobError {
   /// An attempt has been made to show an ad on an Android Activity that has
   /// no window token (such as one that's not done initializing).
   kAdMobErrorNoWindowToken,
+  /// Fallback error for any unidentified cases.
+  kAdMobErrorUnknown,
 };
 #ifdef INTERNAL_EXPERIMENTAL
 // LINT.ThenChange(//depot_firebase_cpp/admob/client/cpp/src_java/com/google/firebase/admob/internal/cpp/ConstantsHelper.java)

admob/src_java/com/google/firebase/admob/internal/cpp/ConstantsHelper.java

@@ -40,6 +40,8 @@ public final class ConstantsHelper {
   public static final int CALLBACK_ERROR_NO_FILL = 7;
 
   public static final int CALLBACK_ERROR_NO_WINDOW_TOKEN = 8;
+
+  public static final int CALLBACK_ERROR_UNKNOWN = 9;
   // LINT.ThenChange(//depot_firebase_cpp/admob/client/cpp/src/include/firebase/admob/types.h)
 
   /**
@@ -68,6 +70,8 @@ public final class ConstantsHelper {
 
   public static final String CALLBACK_ERROR_MESSAGE_NO_WINDOW_TOKEN =
       "Android Activity does not have a window token.";
+
+  public static final String CALLBACK_ERROR_MESSAGE_UNKNOWN = "Unknown error occurred.";
   // LINT.ThenChange(//depot_firebase_cpp/admob/client/cpp/src/include/firebase/admob/types.h)
 
   /** Types of notifications to send back to the C++ side for listeners updates. */

admob/src_java/com/google/firebase/admob/internal/cpp/InterstitialAdHelper.java

@@ -92,14 +92,22 @@ public void run() {
             int errorCode;
             String errorMessage;
             if (mInterstitial == null) {
-              errorCode = ConstantsHelper.CALLBACK_ERROR_NONE;
-              errorMessage = ConstantsHelper.CALLBACK_ERROR_MESSAGE_NONE;
-              mInterstitial = new InterstitialAd(mActivity);
-              mInterstitial.setAdUnitId(mAdUnitId);
-              mInterstitial.setAdListener(new InterstitialAdListener());
+              try {
+                mInterstitial = new InterstitialAd(mActivity);
+                mInterstitial.setAdUnitId(mAdUnitId);
+                mInterstitial.setAdListener(new InterstitialAdListener());
+                errorCode = ConstantsHelper.CALLBACK_ERROR_NONE;
+                errorMessage = ConstantsHelper.CALLBACK_ERROR_MESSAGE_NONE;
+              } catch (IllegalStateException e) {
+                mInterstitial = null;
+                // This exception can be thrown if the ad unit ID was already set.
+                errorCode = ConstantsHelper.CALLBACK_ERROR_ALREADY_INITIALIZED;
+                errorMessage = ConstantsHelper.CALLBACK_ERROR_MESSAGE_ALREADY_INITIALIZED;
+              }
             } else {
               errorCode = ConstantsHelper.CALLBACK_ERROR_ALREADY_INITIALIZED;
               errorMessage = ConstantsHelper.CALLBACK_ERROR_MESSAGE_ALREADY_INITIALIZED;
+
             }
 
             completeInterstitialAdFutureCallback(callbackDataPtr, errorCode, errorMessage);
@@ -152,7 +160,17 @@ public void run() {
                 mLoadAdCallbackDataPtr = CPP_NULLPTR;
               }
             } else {
-              mInterstitial.loadAd(request);
+              try {
+                mInterstitial.loadAd(request);
+              } catch (IllegalStateException e) {
+                synchronized (mInterstitialLock) {
+                  completeInterstitialAdFutureCallback(
+                      mLoadAdCallbackDataPtr,
+                      ConstantsHelper.CALLBACK_ERROR_UNINITIALIZED,
+                      ConstantsHelper.CALLBACK_ERROR_MESSAGE_UNINITIALIZED);
+                  mLoadAdCallbackDataPtr = CPP_NULLPTR;
+                }
+              }
             }
           }
         });
@@ -222,6 +240,9 @@ public void onAdFailedToLoad(int errorCode) {
           callbackErrorCode = ConstantsHelper.CALLBACK_ERROR_NO_FILL;
           callbackErrorMessage = ConstantsHelper.CALLBACK_ERROR_MESSAGE_NO_FILL;
           break;
+        default:
+          callbackErrorCode = ConstantsHelper.CALLBACK_ERROR_UNKNOWN;
+          callbackErrorMessage = ConstantsHelper.CALLBACK_ERROR_MESSAGE_UNKNOWN;
       }
 
       synchronized (mInterstitialLock) {
@@ -233,11 +254,6 @@ public void onAdFailedToLoad(int errorCode) {
       super.onAdFailedToLoad(errorCode);
     }
 
-    @Override
-    public void onAdLeftApplication() {
-      super.onAdLeftApplication();
-    }
-
     @Override
     public void onAdLoaded() {
       synchronized (mInterstitialLock) {