App/UI crashed when create a unknown Cloud Connection

Describe the bug
The app crashed when create a unknown Cloud Connection.

To Reproduce
Steps to reproduce the behavior:

1. Create Cloud Connection
2. Choose SMB Connection
3. Click USE CUSTOM IP
4. Input 'test.com' and click CREATE
5. After it loaded, the app crashes

Screenshots
If applicable, add screenshots to help explain your problem.

Smartphone (please complete the following information):

• Device: Google Pixel 5
• OS: Android 7.1.1
• Rooted: No
• Version: 3.8.5

Crash Logs

java.lang.StringIndexOutOfBoundsException: length=0; regionStart=0; regionLength=-1
	at java.lang.String.substring(String.java:1931)
	at com.amaze.filemanager.ui.dialogs.SmbConnectDialog.onCreateDialog(SmbConnectDialog.java:268)
	at androidx.fragment.app.DialogFragment.prepareDialog(DialogFragment.java:647)
	at androidx.fragment.app.DialogFragment.onGetLayoutInflater(DialogFragment.java:561)
	at androidx.fragment.app.Fragment.performGetLayoutInflater(Fragment.java:1698)
	at androidx.fragment.app.FragmentStateManager.createView(FragmentStateManager.java:492)
	at androidx.fragment.app.FragmentStateManager.moveToExpectedState(FragmentStateManager.java:261)
	at androidx.fragment.app.FragmentManager.executeOpsTogether(FragmentManager.java:1840)
	at androidx.fragment.app.FragmentManager.removeRedundantOperationsAndExecute(FragmentManager.java:1764)
	at androidx.fragment.app.FragmentManager.execPendingActions(FragmentManager.java:1701)
	at androidx.fragment.app.FragmentManager$4.run(FragmentManager.java:488)
	at android.os.Handler.handleCallback(Handler.java:751)
	at android.os.Handler.dispatchMessage(Handler.java:95)
	at android.os.Looper.loop(Looper.java:154)
	at android.app.ActivityThread.main(ActivityThread.java:6119)
	at java.lang.reflect.Method.invoke(Native Method)
	at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
	at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)

Start at com.amaze.filemanager.ui.dialogs.SmbConnectDialog.onCreateDialog, especially line 268 named in the crash log, and reproduce the custom SMB connection flow with test.com. Trace the empty-string substring failure and verify that creating an unknown Cloud Connection no longer crashes.