tree 3e03fe72b89a8e45f7a7423869a1bf12ea4f05ae
parent 91c628d63aa5cd9c6165413946bb9f1171131f60
author Paul Berry <paulberry@google.com> 1614720807 +0000
committer commit-bot@chromium.org <commit-bot@chromium.org> 1614720807 +0000

Migration: fix race condition with null navigationTree.

If the user tries to click around in the migration web UI before the
navigation tree has finished loading, the `navigationTree` global
variable will still be null; we need to allow for this possibility to
avoid a crash.

Bug: https://buganizer.corp.google.com/issues/181067935
Change-Id: I5398ac62bb4eb307aaa48ec39098b6ae0541a6a9
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/188560
Reviewed-by: Samuel Rawlins <srawlins@google.com>
Commit-Queue: Paul Berry <paulberry@google.com>