added safety checks around the scenario when intent bundle are null for authentication activity

Author: pmathew92

auth0/src/main/java/com/auth0/android/Auth0.kt

@@ -72,7 +72,7 @@ public open class Auth0 private constructor(
      * @return Url to call to perform the web flow of OAuth
      */
     public open val authorizeUrl: String
-        get() = domainUrl!!.newBuilder()
+        get() = domainUrl.newBuilder()
             .addEncodedPathSegment("authorize")
             .build()
             .toString()
@@ -83,7 +83,7 @@ public open class Auth0 private constructor(
      * @return Url to call to perform the web logout
      */
     public open val logoutUrl: String
-        get() = domainUrl!!.newBuilder()
+        get() = domainUrl.newBuilder()
             .addEncodedPathSegment("v2")
             .addEncodedPathSegment("logout")
             .build()
@@ -134,7 +134,7 @@ public open class Auth0 private constructor(
         ): Auth0 {
             val domainUrl = ensureValidUrl(domain)
             requireNotNull(domainUrl) { String.format("Invalid domain url: '%s'", domain) }
-            if (instance == null || instance!!.clientId != clientId || instance!!.domainUrl.host != domainUrl.host || instance!!.configurationDomain != configurationDomain) {
+            if (instance == null || instance?.clientId != clientId || instance?.domainUrl?.host != domainUrl.host || instance?.configurationDomain != configurationDomain) {
                 instance = Auth0(clientId, domainUrl, configurationDomain)
             }
             return instance!!

auth0/src/main/java/com/auth0/android/authentication/AuthenticationException.kt

@@ -26,7 +26,10 @@ public class AuthenticationException : Auth0Exception {
 
     public constructor(message: String, cause: Exception? = null) : super(message, cause)
 
-    public constructor(code: String, description: String, cause: Exception) : this(DEFAULT_MESSAGE, cause) {
+    public constructor(code: String, description: String, cause: Exception) : this(
+        DEFAULT_MESSAGE,
+        cause
+    ) {
         this.code = code
         this.description = description
     }
@@ -126,7 +129,10 @@ public class AuthenticationException : Auth0Exception {
         get() = "a0.invalid_configuration" == code
 
     // When a user closes the browser app and in turn, cancels the authentication
-    @Deprecated("This property can refer to both log in and log out actions.", replaceWith = ReplaceWith("isCanceled"))
+    @Deprecated(
+        "This property can refer to both log in and log out actions.",
+        replaceWith = ReplaceWith("isCanceled")
+    )
     public val isAuthenticationCanceled: Boolean
         get() = isCanceled
 
@@ -183,7 +189,7 @@ public class AuthenticationException : Auth0Exception {
     /// When authenticating with web-based authentication using prompt=none and the auth0 session had expired
     public val isLoginRequired: Boolean
         get() = "login_required" == code
-    
+
     /// User is deleted
     public val isRefreshTokenDeleted: Boolean
         get() = "invalid_grant" == code
@@ -205,6 +211,12 @@ public class AuthenticationException : Auth0Exception {
 
     internal companion object {
         internal const val ERROR_VALUE_AUTHENTICATION_CANCELED = "a0.authentication_canceled"
+        internal const val ERROR_KEY_URI_NULL = "a0.auth.authorize_uri"
+        internal const val ERROR_VALUE_AUTHORIZE_URI_INVALID =
+            "Authorization URI is received as null from the intent"
+        internal const val ERROR_KEY_CT_OPTIONS_NULL = "a0.auth.ct_options"
+        internal const val ERROR_VALUE_CT_OPTIONS_INVALID =
+            "Custom tab options are received as null from the intent"
         private const val ERROR_KEY = "error"
         private const val CODE_KEY = "code"
         private const val DESCRIPTION_KEY = "description"

auth0/src/main/java/com/auth0/android/provider/AuthenticationActivity.kt

@@ -7,6 +7,10 @@ import android.net.Uri
 import android.os.Bundle
 import androidx.annotation.VisibleForTesting
 import com.auth0.android.authentication.AuthenticationException
+import com.auth0.android.authentication.AuthenticationException.Companion.ERROR_KEY_CT_OPTIONS_NULL
+import com.auth0.android.authentication.AuthenticationException.Companion.ERROR_KEY_URI_NULL
+import com.auth0.android.authentication.AuthenticationException.Companion.ERROR_VALUE_AUTHORIZE_URI_INVALID
+import com.auth0.android.authentication.AuthenticationException.Companion.ERROR_VALUE_CT_OPTIONS_INVALID
 import com.auth0.android.callback.RunnableTask
 import com.auth0.android.provider.WebAuthProvider.failure
 import com.auth0.android.provider.WebAuthProvider.resume
@@ -68,23 +72,44 @@ public open class AuthenticationActivity : Activity() {
     }
 
     private fun launchAuthenticationIntent() {
-        val extras = intent.extras
-        val authorizeUri = extras!!.getParcelable<Uri>(EXTRA_AUTHORIZE_URI)
-        val customTabsOptions: CustomTabsOptions = extras.getParcelable(EXTRA_CT_OPTIONS)!!
+        val extras: Bundle? = intent.extras
+
+        val authorizeUri = extras?.getParcelable<Uri>(EXTRA_AUTHORIZE_URI)
+        authorizeUri ?: run {
+            deliverAuthenticationFailure(
+                AuthenticationException(
+                    ERROR_KEY_URI_NULL, ERROR_VALUE_AUTHORIZE_URI_INVALID
+                )
+            )
+            return
+        }
+
+        val customTabsOptions: CustomTabsOptions? = extras.getParcelable(EXTRA_CT_OPTIONS)
+        customTabsOptions ?: run {
+            deliverAuthenticationFailure(
+                AuthenticationException(
+                    ERROR_KEY_CT_OPTIONS_NULL, ERROR_VALUE_CT_OPTIONS_INVALID
+                )
+            )
+            return
+        }
+
         val launchAsTwa: Boolean = extras.getBoolean(EXTRA_LAUNCH_AS_TWA, false)
         customTabsController = createCustomTabsController(this, customTabsOptions)
         customTabsController!!.bindService()
-        customTabsController!!.launchUri(authorizeUri!!, launchAsTwa, getInstance(), object : RunnableTask<AuthenticationException> {
-            override fun apply(error: AuthenticationException) {
-                deliverAuthenticationFailure(error)
-            }
-        })
+        customTabsController!!.launchUri(authorizeUri,
+            launchAsTwa,
+            getInstance(),
+            object : RunnableTask<AuthenticationException> {
+                override fun apply(error: AuthenticationException) {
+                    deliverAuthenticationFailure(error)
+                }
+            })
     }
 
     @VisibleForTesting(otherwise = VisibleForTesting.PRIVATE)
     internal open fun createCustomTabsController(
-        context: Context,
-        options: CustomTabsOptions
+        context: Context, options: CustomTabsOptions
     ): CustomTabsController {
         return CustomTabsController(context, options, TwaLauncher(context))
     }
@@ -107,10 +132,7 @@ public open class AuthenticationActivity : Activity() {
 
         @JvmStatic
         internal fun authenticateUsingBrowser(
-            context: Context,
-            authorizeUri: Uri,
-            launchAsTwa: Boolean,
-            options: CustomTabsOptions
+            context: Context, authorizeUri: Uri, launchAsTwa: Boolean, options: CustomTabsOptions
         ) {
             val intent = Intent(context, AuthenticationActivity::class.java)
             intent.putExtra(EXTRA_AUTHORIZE_URI, authorizeUri)