fix crash when using direct jingle init on offline contacts

src/main/java/eu/siacs/conversations/ui/util/PresenceSelector.java

@@ -32,6 +32,7 @@ package eu.siacs.conversations.ui.util;
 import android.app.Activity;
 import android.content.Context;
 import android.util.Pair;
+import android.widget.Toast;
 
 import androidx.appcompat.app.AlertDialog;
 
@@ -60,7 +61,9 @@ public class PresenceSelector {
 
     public static void selectFullJidForDirectRtpConnection(final Activity activity, final Contact contact, final RtpCapability.Capability required, final OnFullJidSelected onFullJidSelected) {
         final String[] resources = RtpCapability.filterPresences(contact, required);
-        if (resources.length == 1) {
+        if (resources.length == 0) {
+            Toast.makeText(activity,R.string.rtp_state_contact_offline,Toast.LENGTH_LONG).show();
+        } else if (resources.length == 1) {
             onFullJidSelected.onFullJidSelected(contact.getJid().withResource(resources[0]));
         } else {
             showPresenceSelectionDialog(activity, contact, resources, onFullJidSelected);