fix #4503: in kivy, catch NotEnoughFunds raised on open channel.

electrum/gui/kivy/uix/dialogs/lightning_open_channel.py

@@ -161,9 +161,11 @@ class LightningOpenChannelDialog(Factory.Popup, Logger):
 
     def do_open_channel(self, conn_str, amount, password):
         coins = self.app.wallet.get_spendable_coins(None, nonlocal_only=True)
-        funding_tx = self.app.wallet.lnworker.mktx_for_open_channel(coins=coins, funding_sat=amount)
+        lnworker = self.app.wallet.lnworker
         try:
-            chan, funding_tx = self.app.wallet.lnworker.open_channel(connect_str=conn_str,
+            funding_tx = lnworker.mktx_for_open_channel(coins=coins, funding_sat=amount)
+            chan, funding_tx = lnworker.open_channel(
+                connect_str=conn_str,
                 funding_tx=funding_tx,
                 funding_sat=amount,
                 push_amt_sat=0,