Make int16Data not nullable

Author: daymxn

firebaseai/LiveAudioExample/Audio/AudioBufferHelpers.swift

@@ -42,7 +42,7 @@ extension AVAudioPCMBuffer {
   /// Gets the underlying `Data` in this buffer.
   ///
   /// Will throw an error if this buffer doesn't hold int16 data.
-  func int16Data() -> Data? {
+  func int16Data() -> Data {
     guard let bufferPtr = audioBufferList.pointee.mBuffers.mData else {
       fatalError("Missing audio buffer list")
     }

firebaseai/LiveAudioExample/ViewModels/LiveViewModel.swift

@@ -130,11 +130,7 @@ class LiveViewModel: ObservableObject {
     let stream = try audioController.listenToMic()
     microphoneTask = Task {
       for await audioBuffer in stream {
-        guard let data = audioBuffer.int16Data() else {
-          logger.error("Failed to convert audio buffer to int16 Data.")
-          continue
-        }
-        await liveSession.sendAudioRealtime(data)
+        await liveSession.sendAudioRealtime(audioBuffer.int16Data())
       }
     }
   }