When favoriting from `show_basic` for courses, the parameters `number`
and `semester` are not passed to the underlying function. Instead, the
`detail_url` is passed, which has to be parsed to get the `number` and
`semester`.
The function `show_detail` for courses was expecting an array of
lecturer oids. When it got only one and therefore not an array but an
int, the line `@lecturers_oid.each` would fail to parse the variable
because it is not an array.
