topics: Fix failure to load from offline state.

[codebu5ter]

This fix first checks for the online status in TopicListScreen, and if found to be online, renders TopicList, which houses all the Redux logic and the call to Selectors that were originally in TopicListScreen.

Fixes #2310

[pulkonet]

Not entirely sure, but I don't think this is the right way to do this. Because if we go this way we would have to change all the screen in the same manner which would be quite a hassle. My take on this would be to change the fetching logic in a manner that you try to fetch the data after the network state changes from offline to online. What do you think?

[codebu5ter]

While you are correct, but at the same time, the only other component that will need such refactoring is the MessageListContainer/ MessageListWeb, since that's what displays the messages (both private and stream messages). I don't think any other screen would require this. Besides, this isOnline logic has to be implemented one way or the other and I've just implemented it inside the component and moved around a couple of functions calls.

[pulkonet]

You are right about implementing it one way or other. But consider a case where you have weak signals and are constantly losing and gaining them, that would create a lot of re-renders for the component but if we change the logic for fetching the messages that won't occur. Also, I understand that this might not be a very frequently occurring case, but this will exist, so taking the other path (which will separate fetching and rendering) sounds like a better choice.

[zulipbot]

Heads up @codebu5ter, we just merged some commits that conflict with the changes your made in this pull request! You can review this repository's recent commits to see where the conflicts occur. Please rebase your feature branch against the upstream/master branch and resolve your pull request's merge conflicts accordingly.

[codebu5ter]

I suppose that is a valid concern. I can modify the logic to include something like a flag that turns true and prevents re-renders, but that would seem hack-y and would not look pretty.
So, I'll look at ways to re-implement the same logic on the API. 👍

[pulkonet]

Yes. Correcting the API logic would be better and also you could directly implement the same corrected logic to Message fetching API.

[codebu5ter]

Indeed. That's what I intend to do.