[Qt] fix possibilty to delete last sendcoins entry

- hide the entry about to be deleted, and if it is the last entry add a
  new one, so that we always have one entry in our list

src/qt/sendcoinsdialog.cpp

@@ -306,12 +306,14 @@ void SendCoinsDialog::updateTabsAndLabels()
 
 void SendCoinsDialog::removeEntry(SendCoinsEntry* entry)
 {
-    entry->deleteLater();
+    entry->hide();
 
-    // If the last entry was removed add an empty one
-    if (!ui->entries->count())
+    // If the last entry is about to be removed add an empty one
+    if (ui->entries->count() == 1)
         addEntry();
 
+    entry->deleteLater();
+
     updateTabsAndLabels();
 }