branch_list: Bail in case of missing worktrees. (#2726)

Z-2632

Release Notes:
- Fixed a crash that occurred when opening a modal branch picker without
a corktree.
369ccc725cPiotr Osiewicz committed on 7/14/2023, 7:41:11 PM· committed by GitHubparentscde5b39c6195e6
1 file changedLine totals unavailable