The commented instructions of the exercise ask to use `No description provided` for the description field when calling `easy_ticket` with an invalid description argument. However, the unit test of that behavior compares the description to `Description not provided` instead.
Previous exercises in that part also use `Description not provided`.
Update the exercise 05_ticket_v2/09_error_trait instructions to use `Description not provided` as an expected default description value when calling `easy_ticket` with no description instead of `No description provided`.
The clone() illustration shows two `s` values in the stack when one of them is the original `s` value which got cloned and the other one should be the new `t` value created from `s`.
Rename the second value from `s` to `t`.
Loup Federico