Prevent NPE

app/src/main/java/eu/faircode/email/Core.java

@@ -1815,9 +1815,12 @@ class Core {
                     IMAPFolder itrash = (IMAPFolder) istore.getFolder(trash.name);
                     Message[] imessages = ifolder.getMessagesByUID(Helper.toLongArray(uids));
 
+                    List<Message> imove = new ArrayList<>();
+                    if (imessages != null)
                         for (Message imessage : imessages)
                             if (imessage instanceof GmailMessage)
                                 try {
+                                    imove.add(imessage);
                                     String[] labels = ((GmailMessage) imessage).getLabels();
                                     for (String label : labels)
                                         if (!folders.containsKey(label)) {
@@ -1829,7 +1832,7 @@ class Core {
                                     Log.e(ex);
                                 }
 
-                    ifolder.moveMessages(imessages, itrash);
+                    ifolder.moveMessages(imove.toArray(new Message[0]), itrash);
 
                     itrash.open(READ_WRITE);
                     try {