The merge example that introduced a logical bug in the article was only visible in the diff because the bug occurred within 3 lines of the added line in the feature branch.
The best way to avoid this issue is automated testing. The second best way is to crack open the file itself, and review the entirety of any functions that changed. Even that approach assumes your encapsulation is nice and you're not introducing issues based on global state though.
While the BitBucket diff is better than nothing (and better than GitHub/GitLab), it's not sufficient to avoid these kinds of issues entirely.
The best way to avoid this issue is automated testing. The second best way is to crack open the file itself, and review the entirety of any functions that changed. Even that approach assumes your encapsulation is nice and you're not introducing issues based on global state though.
While the BitBucket diff is better than nothing (and better than GitHub/GitLab), it's not sufficient to avoid these kinds of issues entirely.