Simplify handling of nullability in `ConnectivityManagerNetworkMonitor`

core/data/src/main/java/com/google/samples/apps/nowinandroid/core/data/util/ConnectivityManagerNetworkMonitor.kt

@@ -30,13 +30,17 @@ import kotlinx.coroutines.channels.awaitClose
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.callbackFlow
 import kotlinx.coroutines.flow.conflate
+import Kotlinx.coroutines.flow.flowOf
 import javax.inject.Inject
 
 class ConnectivityManagerNetworkMonitor @Inject constructor(
     @ApplicationContext private val context: Context,
 ) : NetworkMonitor {
-    override val isOnline: Flow<Boolean> = callbackFlow {
+    override val isOnline: Flow<Boolean> {
         val connectivityManager = context.getSystemService<ConnectivityManager>()
+            ?: return flowOf(false)
+
+        return callbackFlow {
 
             /**
              * The callback's methods are invoked on changes to *any* network, not just the active
@@ -60,7 +64,7 @@ class ConnectivityManagerNetworkMonitor @Inject constructor(
                 }
             }
 
-        connectivityManager?.registerNetworkCallback(
+            connectivityManager.registerNetworkCallback(
                 Builder()
                     .addCapability(NetworkCapabilities.NET_CAPABILITY_INTERNET)
                     .build(),
@@ -70,21 +74,17 @@ class ConnectivityManagerNetworkMonitor @Inject constructor(
             channel.trySend(connectivityManager.isCurrentlyConnected())
 
             awaitClose {
-            connectivityManager?.unregisterNetworkCallback(callback)
+                connectivityManager.unregisterNetworkCallback(callback)
             }
         }
             .conflate()
 
     @Suppress("DEPRECATION")
-    private fun ConnectivityManager?.isCurrentlyConnected() = when (this) {
+    private fun ConnectivityManager.isCurrentlyConnected() = when {
-        null -> false
-        else -> when {
         VERSION.SDK_INT >= VERSION_CODES.M ->
             activeNetwork
                 ?.let(::getNetworkCapabilities)
                 ?.hasCapability(NetworkCapabilities.NET_CAPABILITY_INTERNET)
-                    ?: false
+        else -> activeNetworkInfo?.isConnected
-            else -> activeNetworkInfo?.isConnected ?: false
+    } ?: false
-        }
-    }
 }