【Kotlin】AndroidスマホからWindows共有フォルダのアクセス時に異常終了

<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />

implementation files('libs/jcifs-ng-2.1.6.jar')
implementation group: 'org.slf4j', name: 'slf4j-api', version: '1.7.32'
implementation group: 'org.slf4j', name: 'slf4j-simple', version: '1.7.32'
implementation 'org.jetbrains.kotlinx:kotlinx-coroutines-core:1.5.1'
implementation 'org.jetbrains.kotlinx:kotlinx-coroutines-android:1.5.1'
implementation group: 'org.bouncycastle', name: 'bcprov-jdk15to18', version: '1.69'

import android.os.Bundle
import android.view.View
import android.widget.TextView
import androidx.appcompat.app.AppCompatActivity
import com.app.R
import jcifs.config.PropertyConfiguration
import jcifs.context.BaseContext
import jcifs.smb.NtlmPasswordAuthenticator
import jcifs.smb.SmbFile
import kotlinx.coroutines.DelicateCoroutinesApi
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.GlobalScope
import kotlinx.coroutines.Job
import kotlinx.coroutines.async
import kotlinx.coroutines.coroutineScope
import kotlinx.coroutines.delay
import kotlinx.coroutines.launch
import java.util.Properties
import kotlin.coroutines.CoroutineContext
import kotlinx.coroutines.*


class MainActivity: AppCompatActivity(), CoroutineScope{
    // coroutine準備
    val TAG: String = "MySMB"

    // coroutine準備
    private val job = Job()
    override val coroutineContext: CoroutineContext
        get() = Dispatchers.Main + job

    // 終了時のcoroutineのキャンセル設定
    override fun onDestroy() {
        job.cancel()
        super.onDestroy()
    }

    var ip: String = "192.168.11.30"
    var userName: String = "Administrator"
    var password: String = "Password"
    val smbroot = "smb://" + ip + "/news/99999/"

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

        GlobalScope.launch (Dispatchers.Main) {
            connectSMB(userName, password, ip, smbroot)
            delay(1000L)
        }
    }


    // SMBサーバーに接続する関数
    suspend fun connectSMB(user: String, password: String, domain: String, smbroot: String): SmbFile {
        val tv:TextView = findViewById(R.id.tv_serverData)
        lateinit var smb: SmbFile

        coroutineScope {
            smb = async(Dispatchers.IO) {
                val prop = Properties()
                prop.setProperty("jcifs.smb.client.minVersion", "SMB202")
                prop.setProperty("jcifs.smb.client.maxVersion", "SMB300")
                val baseCxt = BaseContext(PropertyConfiguration(prop))
                val auth = baseCxt.withCredentials(NtlmPasswordAuthenticator(domain, user, password))
                SmbFile(smbroot, auth)
            }.await()

            tv.text = smb.path
            delay(1000L)


            try {
                if (smb.isDirectory()){  ←ここでエラー
                    tv.text = "ディレクトリです"
                    delay(1000L)
                }else{
                    if (smb.exists()){
                        tv.text = "ファイルです"
                        delay(1000L)
                    }else{
                        tv.text = "存在しません"
                        delay(1000L)
                    }
                }
            } catch (e: Exception) {
                tv.text = "error: " + e.message.toString()
            }

        }
        return smb
    }
}