avoid crash when coming first time back from accounts to main activity

app/src/main/kotlin/com/tutpro/baresip/MainActivity.kt

@@ -860,6 +860,9 @@ class MainActivity : AppCompatActivity() {
 
             ACCOUNTS_CODE -> {
                 uaAdapter.notifyDataSetChanged()
+                if ((aorSpinner.selectedItemPosition == -1) && (uas.size > 0))
+                    aorSpinner.setSelection(0)
+                if (aorSpinner.selectedItemPosition >= 0) {
                     val acc = uas[aorSpinner.selectedItemPosition].account
                     if (acc.vmUri != "") {
                         if (acc.vmNew > 0)
@@ -870,6 +873,7 @@ class MainActivity : AppCompatActivity() {
                     } else {
                         voicemailButton.visibility = View.INVISIBLE
                     }
+                }
                 baresipService.setAction("UpdateNotification")
                 startService(baresipService)
             }