My application with mediacord is destroyed

I am trying to create an application that allows me to record audio, save audio and play recorded audio.

The problen :

When I press the button to record or play my application is destroyed.

i have looked that video but i don´t undertan what happen

<!--https://www.youtube.com/watch?v=_Z0AZoTxWYQ-->

I have added this in my manifest

   <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
       <uses-permission android:name="android.permission.RECORD_AUDIO"/>

  class MainActivity : AppCompatActivity() {
        lateinit var recorder: MediaRecorder
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val path: String = Environment.getExternalStorageDirectory().toString() + "/grabacion.mp3"
        recorder = MediaRecorder()

        button.isEnabled = false
        button2.isEnabled = false

        if (ActivityCompat.checkSelfPermission(
                this,
                Manifest.permission.RECORD_AUDIO
            ) != PackageManager.PERMISSION_GRANTED
        )
            ActivityCompat.requestPermissions(
                this, arrayOf(
                    Manifest.permission.RECORD_AUDIO,
                    Manifest.permission.WRITE_EXTERNAL_STORAGE
                ), 111
            )


        button.isEnabled = true
 <!--BUTTON TO RECORD-->
        button.setOnClickListener {
            recorder.setAudioSource(MediaRecorder.AudioSource.MIC)
            recorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP)
            recorder.setAudioEncoder(MediaRecorder.OutputFormat.AMR_NB)
            recorder.setOutputFile(path)
            recorder.prepare()
            recorder.start()

            button2.isEnabled = true
            button.isEnabled = false
        }

        <!--BUTTON STOP-->

        button2.setOnClickListener {
            recorder.stop()
            button.isEnabled = true
            button2.isEnabled = false
        }

        <!--BUTTON PLAY-->

        button3.setOnClickListener {
            val mediaPlayer = MediaPlayer()
            mediaPlayer.setDataSource(path)
            mediaPlayer.prepare()
            mediaPlayer.start()
    
            }
    }
}

I have found the solution,what was causing the problem was

val path: String = Environment.getExternalStorageDirectory().toString() + "/grabacion.mp3"

We need to change it for

val path: String = getExternalFilesDir(null).toString() + "/grabacion.mp3"