[Bugs] Review PR page scrolls to the top occasionally on Viewed check

**Mood:** 😔
**Category:** Bugs

Ocassionally when I press "viewed" on a file while reviewing a PR - the page jumps on top.
I commonly start reviews from the bottom because it has lower scoped files such as tests, which are easily to mark viewed without looking around several files.
So when it jumps to the top, I have to scroll down again, slightly annoying, but otherwise I am enjoying the review experience (except for inability to add per-line review comments of course).

---
| Field | Value |
| --- | --- |
| App version | 1.0.6 |
| OS | Windows 10.0.26200 |
| Theme | GitHub |
| Path | /mywork |
| Tenure | Week 2 |

Start at the /mywork review page and reproduce the issue on Windows 10 by opening a pull request, scrolling near the bottom, and marking a file as Viewed. Confirm that the page remains at the same scroll position instead of jumping to the top; the issue is done when this behavior is stable during review.

索引モデルが issue の本文から書いたものです。