add an initialized flow

The purpose is to signal when the peer has loaded channels from the
database, allowing the caller to differentiate between "channels not yet
loaded" and "no channels at all".

src/commonMain/kotlin/fr/acinq/lightning/io/Peer.kt

@@ -123,7 +123,7 @@ class Peer(
 
     // channels map, indexed by channel id
     // note that a channel starts with a temporary id then switches to its final id once accepted
-    private val _channelsFlow = MutableStateFlow<Map<ByteVector32, ChannelState>>(HashMap())
+    private val _channelsFlow = MutableStateFlow<Map<ByteVector32, ChannelState>>(emptyMap())
     val channelsFlow: StateFlow<Map<ByteVector32, ChannelState>> get() = _channelsFlow
 
     private var _channels by _channelsFlow
@@ -152,6 +152,10 @@ class Peer(
     val currentTipFlow = MutableStateFlow<Pair<Int, BlockHeader>?>(null)
     val onChainFeeratesFlow = MutableStateFlow<OnChainFeerates?>(null)
 
+    // signals when the peer has loaded channels from the database, allowing to differentiate between "channels not yet loaded" and "no channels at all".
+    private val _initialized = MutableStateFlow<Boolean>(false)
+    val initialized get() = _initialized.asSharedFlow()
+
     private val _channelLogger = nodeParams.loggerFactory.newLogger(ChannelState::class)
     private suspend fun ChannelState.process(cmd: ChannelCommand): Pair<ChannelState, List<ChannelAction>> {
         val state = this
@@ -209,6 +213,7 @@ class Peer(
         launch {
             // we don't restore closed channels
             val channels = db.channels.listLocalChannels().filterNot { it is Closed }.associateBy { it.channelId }
+            _initialized.emit(true)
             channels.values.forEach {
                 logger.info { "restoring channel ${it.channelId} from local storage" }
                 val state = WaitForInit