fix bug

Sources/HPRTMP/Network/NetworkClient.swift

@@ -18,6 +18,7 @@ final class RTMPClientHandler: ChannelInboundHandler {
 
   func channelRead(context: ChannelHandlerContext, data: NIOAny) {
     let data = self.unwrapInboundIn(data)
+    guard !data.isEmpty else { return }
     responseCallback(data)
   }
 }
@@ -52,6 +53,7 @@ class NetworkClient: NetworkConnectable {
   private var host: String?
   private var port: Int?
 
+  private var cachedReceivedData: Data = .init()
   private var dataPromise: EventLoopPromise<Data>?
 
   init() {
@@ -89,15 +91,27 @@ class NetworkClient: NetworkConnectable {
   }
 
   func receiveData() async throws -> Data {
-    guard let promise = self.dataPromise else {
-      throw NSError(domain: "RTMPClientError", code: 2, userInfo: [NSLocalizedDescriptionKey: "Data promise is not initialized."])
+    guard let channel = self.channel else {
+      print("Connection not established")
+      throw NSError(domain: "RTMPClientError", code: 1, userInfo: [NSLocalizedDescriptionKey: "Connection not established"])
     }
-    self.dataPromise = channel!.eventLoop.makePromise(of: Data.self)
-    return try await promise.futureResult.get()
+    if !cachedReceivedData.isEmpty {
+      let data = cachedReceivedData
+      cachedReceivedData = Data()
+      return data
+    }
+
+    self.dataPromise = channel.eventLoop.makePromise(of: Data.self)
+    return try await dataPromise!.futureResult.get()
   }
 
   private func responseReceived(data: Data) {
-    self.dataPromise?.succeed(data)
+    cachedReceivedData.append(data)
+    if let dataPromise {
+      dataPromise.succeed(cachedReceivedData)
+      cachedReceivedData = Data()
+      self.dataPromise = nil
+    }
   }
 
   func shutdown() {