Fix NPE when returning from anti-social providers

Signed-off-by: Alex Saveau <saveau.alexandre@gmail.com>

Author: SUPERCILEX

auth/src/main/java/com/firebase/ui/auth/ui/idp/AuthMethodPickerActivity.java

@@ -162,12 +162,22 @@ private void populateIdpList(List<IdpConfig> providerConfigs,
                     this, R.string.fui_progress_dialog_loading) {
                 @Override
                 protected void onSuccess(@NonNull IdpResponse response) {
-                    handler.startSignIn(response);
+                    handleResponse(response);
                 }
 
                 @Override
                 protected void onFailure(@NonNull Exception e) {
-                    handler.startSignIn(IdpResponse.from(e));
+                    handleResponse(IdpResponse.from(e));
+                }
+
+                private void handleResponse(@NonNull IdpResponse response) {
+                    if (!response.isSuccessful()
+                            || AuthUI.SOCIAL_PROVIDERS.contains(response.getProviderType())) {
+                        handler.startSignIn(response);
+                    } else {
+                        finish(response.isSuccessful() ? RESULT_OK : RESULT_CANCELED,
+                                response.toIntent());
+                    }
                 }
             });
 

auth/src/main/java/com/firebase/ui/auth/viewmodel/idp/SocialProviderResponseHandler.java

@@ -7,6 +7,7 @@
 import android.support.annotation.Nullable;
 import android.support.annotation.RestrictTo;
 
+import com.firebase.ui.auth.AuthUI;
 import com.firebase.ui.auth.ErrorCodes;
 import com.firebase.ui.auth.FirebaseUiException;
 import com.firebase.ui.auth.IdpResponse;
@@ -24,7 +25,6 @@
 import com.google.firebase.auth.AuthResult;
 import com.google.firebase.auth.EmailAuthProvider;
 import com.google.firebase.auth.FirebaseAuthUserCollisionException;
-import com.google.firebase.auth.PhoneAuthProvider;
 
 @RestrictTo(RestrictTo.Scope.LIBRARY_GROUP)
 public class SocialProviderResponseHandler extends AuthViewModelBase<IdpResponse> {
@@ -37,10 +37,9 @@ public void startSignIn(@NonNull final IdpResponse response) {
             setResult(Resource.<IdpResponse>forFailure(response.getError()));
             return;
         }
-        if (response.getProviderType().equals(EmailAuthProvider.PROVIDER_ID)
-                || response.getProviderType().equals(PhoneAuthProvider.PROVIDER_ID)) {
-            setResult(Resource.forSuccess(response));
-            return;
+        if (!AuthUI.SOCIAL_PROVIDERS.contains(response.getProviderType())) {
+            throw new IllegalStateException(
+                    "This handler cannot be used with email or phone providers");
         }
         setResult(Resource.<IdpResponse>forLoading());