May has shown real political strength in realising that an error was made and has now sought to clarify it. The manufactured outrage from Corbyn and co is pretty cynical tbh......I'd rather have a politician who reacts to an error than one like Corbyn (I won't use nuclear weapons so we'll just build the boats and not arm them) who cannot be persuaded to change his mind when he is in the wrong.......
..this wasn't an 'error', it was something May wanted to introduce. What has happened is that she's realised this election isn't the cake walk she imagined, the Conservatives are complacement. These policy items are not 'errors', they are ideology.