Redux: Safe state updates in reducers

Below is correct way of updating state in reducers. Reason why we are doing it this way is, that we want to create new state in memory. Then Redux knows that something has changed and React can rerender app.
With examples on the left we are referencing the same array/object.
With examples on the right we are creating new array/object.
_.omit is using lodash library, available at lodash.com