Fix the ticket tui so it does not panic

The tui for ticket uses indexing in order to have quicker unchecked
access into data structures for the data needed that gets displayed in
the tui. However, you can't index empty data. We add a check for this in
places that expect data to exist so that nothing will cause a panic. We
also add fixes to handle the fact that you can't divide by zero in our
index modifying logic when pressing the left/right/up/down arrow keys.
With this the tui shouldn't panic anymore and can work in an empty
state.

Closes: 4c37e800-2e38-11ea-b6e0-32f54a3ad7cd 'Having no tickets causes
the TUI to crash'

1 files changed, 17 insertions, 0 deletions

diff --git a/.dev-suite/ticket/closed/having-no-tickets-causes-the-tui-to-crash.toml b/.dev-suite/ticket/closed/having-no-tickets-causes-the-tui-to-crash.toml
new file mode 100644
index 0000000..960ee5d
--- /dev/null
+++ b/.dev-suite/ticket/closed/having-no-tickets-causes-the-tui-to-crash.toml
@@ -0,0 +1,17 @@
+title = 'Having no tickets causes the TUI to crash'
+status = 'Closed'
+id = '4c37e800-2e38-11ea-b6e0-32f54a3ad7cd'
+assignees = [[
+    '64c00ccc-761e-4484-86ac-904e461bb300',
+    'Michael Gattozzi',
+]]
+description = '''
+Due to how the ticket tui uses indexing to avoid bounds checks this causes an
+issue when you're, well, out of bounds. This was handled properly for when we
+have n > 0 elements in the open or closed ticket arrays. An empty state for
+when there are no tickets and a check for an empty collection need to be
+created so that the indexing will be avoided and cause a crash.
+'''
+version = 'V1'
+
+[comments]