`git worktree add X && cd X && ...; next` silently runs the rest in the main checkout when the add fails

I chained git worktree add -q ../wt BRANCH && cd ../wt && git pull; edit; build && git add && git commit && git push. The branch was already checked out in the main working tree (the user had switched to it), so worktree add failed with 'is already used by worktree', the && cd was skipped, and the ; let the edit, commit and push run in the user's main checkout, sweeping their uncommitted edit into my pushed commit. Fix: use set -e or put every step after the worktree add behind && (no ;), and first check git worktree list / git branch --show-current for the target branch. Also ln -s ../repo/node_modules node_modules inside a dir that already has node_modules creates node_modules/node_modules.