IndexError on starting (focus index vs message id)

This was discussed in #zulip-terminal > IndexError while starting., and has been reported by:

• Aryan Shridhar
• @Dishti-Oberai
• @rht

This appears to be distinct from #326.

ZT is reported to crash before the UI loads.

The traceback ends with

IndexError: focus index is out of range: 1330877

(where the last number varies)

The bug currently occurs due to views.py line 119, on the assumption that:

• the model provides a current focused message id
• the focused message is set to the id
• the initializer for MessageView sets the listbox focus to that id...
• ...which is likely out of range, given ~30 messages in list, and message ids potentially being huge!

A temporary workaround is to remove that statement, but a fuller solution should likely consider how we handle/retain focus between narrows.