Bug: FixedSizeList scrollToItem "center" strategy sometimes scrolls item out of view

[chuckdries]

Certain combinations of height, itemSize, and itemCount parameters can cause the "center" mode of scrollToItem to behave incorrectly. In this example sandbox, clicking the "scroll to 41" button consistently scrolls item 41 out of view (tested in chrome)

https://codesandbox.io/s/react-window-center-scroll-bug-29r22j?file=/src/App.tsx

We appear to be hitting this case when we shouldn't be:

react-window/src/FixedSizeList.js

Line 69 in 51ec3f8

return 0; // near the beginning

though I don't understand that function well enough to see exactly where it's going wrong.

[134355]

There is a problem with the height setting