How to resolve this java.lang.NullPointerException: Attempt to invoke virtual method 'on a null object reference?

Question

I've implemented the fingerprint feature into my Android app and I'm using jetpack compose. This is my Biometric code.

import android.content.Context 
import android.os.Build 
import android.util.Log 
import android.widget.Toast 
import androidx.biometric.BiometricManager 
import androidx.biometric.BiometricPrompt 
import androidx.compose.runtime.Composable 
import androidx.compose.ui.platform.LocalContext 
import androidx.core.content.ContextCompat 
import androidx.fragment.app.FragmentActivity 
import sahalwallet.app.R 
import sahalwallet.app.theme.bu 
import sahalwallet.app.theme.col 
import sahalwallet.app.theme.ui

class Biometric:FragmentActivity() {


    fun status(con: Context): Boolean {
        var result = false
        val biometricManager = BiometricManager.from(con)

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.R) {
            when (biometricManager.canAuthenticate(BiometricManager.Authenticators.DEVICE_CREDENTIAL or BiometricManager.Authenticators.BIOMETRIC_STRONG)) {
                BiometricManager.BIOMETRIC_SUCCESS -> result = true
                BiometricManager.BIOMETRIC_ERROR_NO_HARDWARE -> result = false
                BiometricManager.BIOMETRIC_ERROR_HW_UNAVAILABLE -> result = false
                BiometricManager.BIOMETRIC_ERROR_NONE_ENROLLED -> result = false
                BiometricManager.BIOMETRIC_ERROR_SECURITY_UPDATE_REQUIRED ->
                    result = true
                BiometricManager.BIOMETRIC_ERROR_UNSUPPORTED ->
                    result = true
                BiometricManager.BIOMETRIC_STATUS_UNKNOWN ->
                    result = false
            }
        } else {
            when (biometricManager.canAuthenticate(BiometricManager.Authenticators.BIOMETRIC_STRONG)) {
                BiometricManager.BIOMETRIC_SUCCESS -> result = true
                BiometricManager.BIOMETRIC_ERROR_NO_HARDWARE -> result = false
                BiometricManager.BIOMETRIC_ERROR_HW_UNAVAILABLE -> result = false
                BiometricManager.BIOMETRIC_ERROR_NONE_ENROLLED -> result = false
                BiometricManager.BIOMETRIC_ERROR_SECURITY_UPDATE_REQUIRED ->
                    result = true
                BiometricManager.BIOMETRIC_ERROR_UNSUPPORTED ->
                    result = true
                BiometricManager.BIOMETRIC_STATUS_UNKNOWN ->
                    result = false
            }
        }
        return result
    }

    fun authenticate(
        activity: FragmentActivity,
        title: String,
        otherOption: String,
        onError: (Int, CharSequence) -> Unit,
        onSuccess: (BiometricPrompt.AuthenticationResult) -> Unit,
        onFailed: () -> Unit,
    ) {
        Log.d("activity is =>",activity.toString())
        val executor =ContextCompat.getMainExecutor(activity)

        val biometricPrompt = BiometricPrompt(activity, executor,
            object : BiometricPrompt.AuthenticationCallback() {
                override fun onAuthenticationError(
                    errorCode: Int,
                    errString: CharSequence
                ) {
                    super.onAuthenticationError(errorCode, errString)
                    onError(errorCode, errString)
                }

                override fun onAuthenticationSucceeded(
                    result: BiometricPrompt.AuthenticationResult
                ) {
                    super.onAuthenticationSucceeded(result)
                    onSuccess(result)
                }

                override fun onAuthenticationFailed() {
                    super.onAuthenticationFailed()
                    onFailed()
                }
            })
        val promptInfo: BiometricPrompt.PromptInfo = BiometricPrompt.PromptInfo.Builder()
            .setTitle(title)
            .setNegativeButtonText(otherOption)
            .build()
        biometricPrompt.authenticate(promptInfo)

    }

    @Composable
    fun BiometricUI() {
        val context = LocalContext.current
        if (status(context)) {
            bu.Icon(
                iconEnd = R.drawable.fingerprint,
                round = ui.tinyHeight,
                bg = col.whiteBrush,
                height = 90,
                action = {

                    /**TODO
                     * We need to pass an object of FragmentActivity into the activity parameter
                     */

                    authenticate(
                        activity = this@Biometric,
                        title = "Authentication Required",
                        otherOption = "Password",
                        onSuccess = {
                            runOnUiThread {
                                Toast.makeText(
                                    context,
                                    "Authenticated successfully",
                                    Toast.LENGTH_SHORT
                                )
                                    .show() //                                isAuthenticated.value = true
                            }
                        },
                        onError = { _, _ ->
                            /*
                        On Clicking on Password
                         */

                        },
                        onFailed = {
                            runOnUiThread {
                                Toast.makeText(
                                    context,
                                    "Authentication failed",
                                    Toast.LENGTH_SHORT
                                )
                                    .show()

                            }
                        }
                    )
                }
            )
        }
    } }

val fingerprint = Biometric()

And in my code I'm calling fingerprint.BiometricUI() And I'm using this into some Composable in my code and this is also showing the biometric icon so when I click this the issue is coming:

java.lang.NullPointerException: Attempt to invoke virtual method 'java.util.concurrent.Executor android.content.Context.getMainExecutor()' on a null object reference

I tried to activity.mainExecutor and ContextCompt.getMainexecutor but both are giving the same issue!

java.util.concurrent.Executor android.content.Context.getMainExecutor()