App works on Android studio but not on device

Question

I made an app to help my elderly father to share photos from whatsapp to Google photos.

I learned programming to do it so it's my first program... Took a while but it runs in android studio and on many phones -

Just not on my father's ! :-(

I tried to update he's phone but it didn't work.

What do i need to check so i can find out?

EDIT:

sorry - i am such a beginner that i don't even know what to look for to upload...

i am attaching the "about software" of my fathers non-working phone:

print screen

and the "about software" of my son's phone - which works:

print screen

and this is the android manifest file:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.beser.qs3">
    <uses-permission android:name="anandroid.permission.WRITE_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.INTERNET"/>
    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="אריאל, תשמור לי"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:requestLegacyExternalStorage="true"
        android:theme="@style/Theme.QS3">
        <provider
            android:name="androidx.core.content.FileProvider"
            android:authorities="com.example.qs3.fileprovider"
            android:grantUriPermissions="true"
            android:exported="false">
            <meta-data
                android:name="android.support.FILE_PROVIDER_PATHS"
                android:resource="@xml/filepaths" />
        </provider>

        <activity
            android:name="com.beser.qs3.MainActivity"
            android:label=" "
            android:exported="true">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

    </application>

</manifest>

and this line:

    @RequiresApi(Build.VERSION_CODES.O)

also, here is my wife's phone error log:

java.lang.RuntimeException: Unable to start activity ComponentInfo{com.beser.qs3/com.beser.qs3.MainActivity}: java.lang.IllegalArgumentException: fromIndex(0) > toIndex(-1)
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3322)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3471)
    at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83)
    at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
    at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2058)
    at android.os.Handler.dispatchMessage(Handler.java:107)
    at android.os.Looper.loop(Looper.java:226)
    at android.app.ActivityThread.main(ActivityThread.java:7592)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:539)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:950)
Caused by: java.lang.IllegalArgumentException: fromIndex(0) > toIndex(-1)
    at java.util.ArrayList.subListRangeCheck(ArrayList.java:1018)
    at java.util.ArrayList.subList(ArrayList.java:1008)
    at com.beser.qs3.data_list.load(data_list.kt:69)
    at com.beser.qs3.MainActivity.onCreate(MainActivity.kt:40)
    at android.app.Activity.performCreate(Activity.java:7916)
    at android.app.Activity.performCreate(Activity.java:7903)
    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1307)
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3297)
    ... 11 more

EDIT2:

here is the onCreate method:

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)


        if (ContextCompat.checkSelfPermission(this,
                android.Manifest.permission.READ_EXTERNAL_STORAGE)
            != PackageManager.PERMISSION_GRANTED) {
                ActivityCompat.requestPermissions(this,
                    arrayOf(android.Manifest.permission.READ_EXTERNAL_STORAGE),
                    1)
            }

        setContentView(R.layout.activity_main)

        myDataset = data_list().load()

        val recyclerView = findViewById<RecyclerView>(R.id.recycler_view_id)

        recyclerView.adapter = RvAdaptor(myDataset,this,applicationContext)
        recyclerView.layoutManager = GridLayoutManager(applicationContext,2)
    }

and the datalist object:

    @RequiresApi(Build.VERSION_CODES.O)
    fun load(): MutableList<Image_data> {
        var imagelist = mutableListOf<Image_data>()
        var i = 0
        var j = 0
        var dir : File
        var files : List<File>
        var file: File
        var max : Int
        var image_date: Date
        var slot_date: Date
        var test_max = 0
        dir = File("/storage/emulated/0/Android/media/com.whatsapp/WhatsApp/Media/WhatsApp Images")
        if (dir.isDirectory){
            files = dir.listFiles().reversed()
            max = files.lastIndex
            if (max > 50) max = 50
            while (i <= max) {
                file = files[i]
                image_date = Date(file.lastModified())
                slot_date = image_date
                j = 0
                test_max = imagelist.lastIndex
                if (test_max != -1) slot_date = imagelist[0].date
                //(testModified.after(lastModified)) = dont put it here
                // (j = test_max)  = reached end of the line (+1) -> get out with this j (=end of line +1)
                // (test_max = -1) = empty list = get out with j = 0
                while ((slot_date.after(image_date)) and (j <= test_max) and (test_max != -1)) {
                    j++
                    if (j<=test_max) slot_date = imagelist[j].date
                }
                if (file.isFile) imagelist.add(j, Image_data(file.absolutePath, image_date, false))
                i++
            }
        }
        i = 0
        dir =  File("/storage/emulated/0/Android/media/com.whatsapp/WhatsApp/Media/WhatsApp Video")
        if (dir.isDirectory) {
                files = dir.listFiles().reversed()
                max = files.lastIndex
                if (max > 50) max = 50
                while (i <= max) {
                    file = files[i]
                    image_date = Date(file.lastModified())
                    slot_date = image_date
                    j = 0
                    test_max = imagelist.lastIndex
                    if (test_max != -1) slot_date = imagelist[0].date
                    //(testModified.after(lastModified)) = dont put it here
                    // (j >= test_max)  = reached end of the line (+1) -> get out with this j (=end of line +1)
                    // (test_max = -1) = empty list = get out with j = 0
                    while ((slot_date.after(image_date)) and (j <= test_max) and (test_max != -1)) {
                        j++
                        if (j<=test_max) slot_date = imagelist[j].date
                    }
                    if (file.isFile) imagelist.add(j, Image_data(file.absolutePath, image_date, false))
                    i++
                }
        }
        return imagelist.subList(0,min(50,imagelist.lastIndex))
    }
}