* Do not redirect when the sequenceId is not valid
That is, if firstSequenceId is null or undefined. This prevents the url
becoming bogus but does cause the course contents display to become stuck
with the loading message.
* Detect invalid sequence when loading
If the course has no sections or the first section has no sub-sections,
then sequence will be null. Before the redirection fix, this would cause an
error, but after, the sequenceStatus never leaves the loading state. Thus,
if still loading and the sequence is null, return the no.content message.
* Check sequenceId instead of sequence
From David Joy:
During initial page load, I expect there's a period of time before the
course blocks API and the sequence metadata API come back where the
sequenceStatus is loading but the sequence is still false, meaning that
we'll see a flash of this 'no content' messaging for a moment before the
data comes in.
If we instead check whether sequenceId is null here, that may give us a
more accurate condition. The sequenceId in redux is only populated when we
begin to request a sequence (fetchSequence thunk). If we have no sequence
ID in the URL route, then fetchSequence never happens and the sequenceId in
redux stays null.
* Fix up some additional errors Piotr found
This fixes errors caused by deleting units or subsections.
* Move test for unit validity to SequenceContent
* Moving model-store into “generic” sub-directory.
Also adding a README.md to explain what belongs in “generic”
* Moving user-messages into “generic” sub-directory.
* Moving PageLoading into “generic” sub-directory.
* Moving “tabs” module into “generic” sub-directory.
* Moving InstructorToolbar and MasqueradeWidget up to instructor-toolbar.
The masquerade widget is a sub-module of instructor-toolbar.
* Co-locating celebration APIs with celebration utils.
Also adding an ADR about thunk/API naming conventions and making some other areas of the code adhere to it.
* Moving courseware data (thunks, api) into the courseware module.
Note that cousre-home/data/api still uses normalizeBlocks - this should be fixed so it’s not reaching across. Maybe we pull that particular API up top.
This PR includes a few TODOs for things I saw, as well as a tiny bit of whitespace cleanup.
TNL-7191 - We didn’t fully protect against sequences with no units. The next/previous buttons now check whether there is a unit ID and construct a URL without if one doesn’t exist. When we load a sequence without units, we now show a message to the user so the page doesn’t look broken.
