Why Text to speech(TTS) object becomes null even after being initialized?

Question

I'm having trouble with ttsvariable . It becomes null, even if the Text to speech object has been initialized.

Inside ShowLabel() function, I want to use tts for texts of firstObject variable. ShowLabel() function receives a List<> of FirebaseVisionImageLabel objects. I'm facing problem on speaking the text inside ShowLabel(). Though the console logs the Boolean to true and the speak() inside OnInit() work.

I have set a checker ttsIsInitialized which is Boolean type, so it needs to be true before the speak() on showLabel() runs. But it gives me null. Any help would be great. If there is a best way to do this, please tell me.

So, For now my issue is tts inside Showlabel() always becomes null. Can someone point out where's my mistake?

This is a project on FirebaseQuickStart
https://github.com/firebase/quickstart-android/tree/master/mlkit

LivePreviewActivity

class LivePreviewActivity : AppCompatActivity(), OnRequestPermissionsResultCallback, TextToSpeech.OnInitListener {

    private var cameraSource: CameraSource? = null
    private var tts: TextToSpeech? = null
    var firstObject = ""


 override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_live_preview)

        tts = TextToSpeech(this, this)

    }
fun showLabel(labels: List<FirebaseVisionImageLabel>?) {
        if (!ttsIsInitialized) {
            Log.d(TAG, "TTS not Initialized")
            Log.d("Boolean", ttsIsInitialized.toString())
        } else {
            firstObject = labels!!.first().text
            tts!!.speak(firstObject, TextToSpeech.QUEUE_FLUSH, null, "")
            Log.d("Boolean", ttsIsInitialized.toString())
        }
    }

    override fun onInit(status: Int) {

        if (status == TextToSpeech.SUCCESS) {
            val result = tts!!.setLanguage(Locale.US)

            if (result == TextToSpeech.LANG_MISSING_DATA || result == TextToSpeech.LANG_NOT_SUPPORTED) {
                Log.e("TTS","The Language specified is not supported!")
            } else {
                Log.d("TTS", "Initilization Successful")
                tts!!.speak("This is a test", TextToSpeech.QUEUE_FLUSH, null, "")
                cameraSource?.setMachineLearningFrameProcessor(ImageLabelingProcessor())
                ttsIsInitialized = true
            }
        } else {
            Log.e("TTS", "Initilization Failed!")
        }

    }

ImageLabelingProcessor

class ImageLabelingProcessor : VisionProcessorBase<List<FirebaseVisionImageLabel>>() {

    private val detector: FirebaseVisionImageLabeler = FirebaseVision.getInstance().onDeviceImageLabeler

    override fun stop() {
        try {
            detector.close()
        } catch (e: IOException) {
            Log.e(TAG, "Exception thrown while trying to close Text Detector: $e")
        }
    }

    override fun detectInImage(image: FirebaseVisionImage): Task<List<FirebaseVisionImageLabel>> {
        return detector.processImage(image)
    }

    override fun onSuccess(
        originalCameraImage: Bitmap?,
        labels: List<FirebaseVisionImageLabel>,
        frameMetadata: FrameMetadata,
        graphicOverlay: GraphicOverlay
    ) {
        graphicOverlay.clear()
        originalCameraImage.let { image ->
            val imageGraphic = CameraImageGraphic(graphicOverlay, image)
            graphicOverlay.add(imageGraphic)
        }
        val labelGraphic = LabelGraphic(graphicOverlay, labels)
        graphicOverlay.add(labelGraphic)
        graphicOverlay.postInvalidate()

        val livePreview = LivePreviewActivity()
        livePreview.showLabel(labels)
        livePreview.labels = labels
    }

    override fun onFailure(e: Exception) {
        Log.w(TAG, "Label detection failed.$e")
    }

    companion object {
        private const val TAG = "ImageLabelingProcessor"
    }
}

Logcat

2019-03-09 14:54:50.979 9658-9658/com.google.firebase.samples.apps.mlkit E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.google.firebase.samples.apps.mlkit, PID: 9658
    kotlin.KotlinNullPointerException
        at com.google.firebase.samples.apps.mlkit.kotlin.LivePreviewActivity.showLabel(LivePreviewActivity.kt:76)
        at com.google.firebase.samples.apps.mlkit.kotlin.imagelabeling.ImageLabelingProcessor.onSuccess(ImageLabelingProcessor.kt:51)
        at com.google.firebase.samples.apps.mlkit.kotlin.imagelabeling.ImageLabelingProcessor.onSuccess(ImageLabelingProcessor.kt:19)
        at com.google.firebase.samples.apps.mlkit.kotlin.VisionProcessorBase$detectInVisionImage$1.onSuccess(VisionProcessorBase.kt:98)
        at com.google.android.gms.tasks.zzn.run(Unknown Source:4)
        at android.os.Handler.handleCallback(Handler.java:873)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:193)
        at android.app.ActivityThread.main(ActivityThread.java:6669)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)
2019-03-09 14:54:50.983 1881-1952/system_process W/ActivityManager:   Force finishing activity com.google.firebase.samples.apps.mlkit/.kotlin.LivePreviewActivity
2019-03-09 14:54:50.997 9658-9658/com.google.firebase.samples.apps.mlkit I/Process: Sending signal. PID: 9658 SIG: 9
2019-03-09 14:54:51.004 1596-1596/? E/lowmemorykiller: Error writing /proc/9658/oom_score_adj; errno=22
2019-03-09 14:54:51.026 1712-9704/? E/Camera3-OutputStream: getBufferLockedCommon: Stream 0: Can't dequeue next output buffer: Broken pipe (-32)
2019-03-09 14:54:51.026 1712-9704/? E/Camera3-Device: RequestThread: Can't get output buffer, skipping request: Broken pipe (-32)