Android Studio getPixel of CameraX Bitmap error (Kotlin)

Question

I made an android app (Android Studio + Kotlin) that uses CameraX. So this is my code to start the camera:

private fun startCamera() {
        val cameraProviderFuture = ProcessCameraProvider.getInstance(this)

        cameraProviderFuture.addListener(Runnable {
            // Used to bind the lifecycle of cameras to the lifecycle owner
            val cameraProvider: ProcessCameraProvider = cameraProviderFuture.get()

            // Preview
            val preview = Preview.Builder()
                .build()
                .also {
                    it.setSurfaceProvider(viewFinder.surfaceProvider)
                }

            // Select back camera as a default
            val cameraSelector = CameraSelector.DEFAULT_BACK_CAMERA

            try {
                // Unbind use cases before rebinding
                cameraProvider.unbindAll()

                // Bind use cases to camera
                cameraProvider.bindToLifecycle(
                    this, cameraSelector, preview
                )

            } catch (exc: Exception) {
                Log.e(TAG, "Use case binding failed", exc)
            }

        }, ContextCompat.getMainExecutor(this))
    }

Now I wanted to get a bitmap of the viewFinder so that I can determine the color of the pixel in the center:

val bitmap = viewFinder.bitmap
val pixel = bitmap?.getPixel(width / 2, height / 2 - 30)

val pixel2 = if (pixel != null) pixel else -1

bitmap is Bitmap? and pixel is Int?

When I run the app everything works completely fine but then sometimes it crashes and shoots out this error:

at com.example.colorblind.MainActivity$onCreate$r$1.run(MainActivity.kt:116)

Line 116 is the line with val pixel = bitmap?.getPixel(width / 2, height / 2 - 30). If I then add a line before the code so that it hops to line 117 everything works perfectly fine again until the same error occurs. Then I need to change the line again. How can I fix this problem because I can't publish the app like this if it sometimes randomly crashes while opening.

I hope I was able to explain the problem properly.