For spectators, the chunk of page_params that originates from
do_events_register isn’t assigned until ui_init.js. That means the
TypeScript type of page_params is mostly a lie during module load
time: reading a parameter too early silently results in undefined
rather than the declared type, with unpredictable results later on.
We want to make such an early read into an immediate runtime error,
for both users and spectators consistently, and pave the way for
runtime validation of the page_params type. As a first step, split
out the subset of fields that pertain to the current user.
Signed-off-by: Anders Kaseorg <anders@zulip.com>
page_params.narrow may be undefined, page_params.server_sentry_dsn may
be null but not undefined, and page_params.user_id may be 0 (for
spectators) but not undefined.
Signed-off-by: Anders Kaseorg <anders@zulip.com>
While `user_id` from `page_params` is marked as `number | undefined`,
when fuctions in this file are called, `page_params.user_id` will
never be undefined. Verifying from all of callers of
`initialize_with_current_user`, this is because when user is able
to create and initialize a stream, this user is authenticated and
thus a `user_id` is always available. Therefore, adding an assertion
when undefined user id is detected to handle a confirmed error.
