qt open channel: early return if fields are left empty

closes #5934

electrum/gui/qt/channels_list.py

@@ -256,4 +256,6 @@ class ChannelsList(MyTreeView):
         else:
             funding_sat = amount_e.get_amount()
         connect_str = str(remote_nodeid.text()).strip()
+        if not connect_str or not funding_sat:
+            return
         self.parent.open_channel(connect_str, funding_sat, 0)

electrum/gui/qt/confirm_tx_dialog.py

@@ -175,6 +175,7 @@ class ConfirmTxDialog(TxEditor, WindowModalDialog):
         password = self.pw.text() or None
         if self.password_required:
             if password is None:
+                self.main_window.show_error(_("Password required"), parent=self)
                 return
             try:
                 self.wallet.check_password(password)