wallet: handle exception when deleting last addr from imported wallet

fixes #6347

electrum/gui/qt/main_window.py

@@ -1949,8 +1949,13 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, Logger):
         return self.create_list_tab(l)
 
     def remove_address(self, addr):
-        if self.question(_("Do you want to remove {} from your wallet?").format(addr)):
+        if not self.question(_("Do you want to remove {} from your wallet?").format(addr)):
+            return
+        try:
             self.wallet.delete_address(addr)
+        except UserFacingException as e:
+            self.show_error(str(e))
+        else:
             self.need_update.set()  # history, addresses, coins
             self.clear_receive_tab()
 

electrum/wallet.py

@@ -2215,7 +2215,7 @@ class Imported_Wallet(Simple_Wallet):
         if not self.db.has_imported_address(address):
             return
         if len(self.get_addresses()) <= 1:
-            raise Exception("cannot delete last remaining address from wallet")
+            raise UserFacingException("cannot delete last remaining address from wallet")
         transactions_to_remove = set()  # only referred to by this address
         transactions_new = set()  # txs that are not only referred to by address
         with self.lock: