RBF: make sure we know the fee for the old txn

related #4306

gui/kivy/uix/dialogs/tx_dialog.py

@@ -135,6 +135,9 @@ class TxDialog(Factory.Popup):
     def do_rbf(self):
         from .bump_fee_dialog import BumpFeeDialog
         is_relevant, is_mine, v, fee = self.wallet.get_wallet_delta(self.tx)
+        if fee is None:
+            self.app.show_error(_("Can't bump fee: unknown fee for original transaction."))
+            return
         size = self.tx.estimated_size()
         d = BumpFeeDialog(self.app, fee, size, self._do_rbf)
         d.open()

gui/qt/history_list.py

@@ -345,7 +345,8 @@ class HistoryList(MyTreeWidget, AcceptFileDragDrop):
                            lambda bound_c=c: self.editItem(item, bound_c))
         menu.addAction(_("Details"), lambda: self.parent.show_transaction(tx))
         if is_unconfirmed and tx:
-            rbf = is_mine and not tx.is_final()
+            # note: the current implementation of RBF *needs* the old tx fee
+            rbf = is_mine and not tx.is_final() and fee is not None
             if rbf:
                 menu.addAction(_("Increase fee"), lambda: self.parent.bump_fee_dialog(tx))
             else:

gui/qt/main_window.py

@@ -3138,6 +3138,9 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, PrintError):
 
     def bump_fee_dialog(self, tx):
         is_relevant, is_mine, v, fee = self.wallet.get_wallet_delta(tx)
+        if fee is None:
+            self.show_error(_("Can't bump fee: unknown fee for original transaction."))
+            return
         tx_label = self.wallet.get_label(tx.txid())
         tx_size = tx.estimated_size()
         d = WindowModalDialog(self, _('Bump Fee'))