App Crashes on changing downloads directory

[pravinyo]

When Trying to set new downloads folder, App crashes,

Logs:
--------- beginning of crash
2020-05-19 17:59:43.631 3901-3901/com.allsoftdroid.audiobook E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.allsoftdroid.audiobook, PID: 3901
java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=75535, result=-1, data=Intent { dat=content://com.android.providers.downloads.documents/tree/raw:/storage/emulated/0/Download/Box flg=0xc3 }} to activity {com.allsoftdroid.audiobook/com.allsoftdroid.audiobook.presentation.MainActivity}: java.lang.StringIndexOutOfBoundsException: length=1; index=20
at android.app.ActivityThread.deliverResults(ActivityThread.java:4905)
at android.app.ActivityThread.handleSendResult(ActivityThread.java:4946)
at android.app.servertransaction.ActivityResultItem.execute(ActivityResultItem.java:51)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2040)
at android.os.Handler.dispatchMessage(Handler.java:107)
at android.os.Looper.loop(Looper.java:224)
at android.app.ActivityThread.main(ActivityThread.java:7520)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:539)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:950)
Caused by: java.lang.StringIndexOutOfBoundsException: length=1; index=20
at java.lang.String.substring(String.java:2027)
at com.allsoftdroid.audiobook.feature_settings.SettingsFragment.onActivityResult(SettingsFragment.kt:191)
at androidx.fragment.app.FragmentActivity.onActivityResult(FragmentActivity.java:170)
at android.app.Activity.dispatchActivityResult(Activity.java:8249)
at android.app.ActivityThread.deliverResults(ActivityThread.java:4898)
at android.app.ActivityThread.handleSendResult(ActivityThread.java:4946) 
at android.app.servertransaction.ActivityResultItem.execute(ActivityResultItem.java:51) 
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135) 
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2040) 
at android.os.Handler.dispatchMessage(Handler.java:107) 
at android.os.Looper.loop(Looper.java:224) 
at android.app.ActivityThread.main(ActivityThread.java:7520) 
at java.lang.reflect.Method.invoke(Native Method) 
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:539) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:950)