fix: FlatList initialScrollIndex

[efstathiosntonas]

Items above initialScrollIndex on a fixed height list won't render, there are numerous bugs on react-native FlatList regarding this issue dated even back to 2015:

• [FlatList] Rows aren't rendered until scroll facebook/react-native#1831
• ListView (or perhaps ScrollView) disappears after running in background for several minutes facebook/react-native#8607
• [FlatList] Sometimes FlatList rows are rendered, but not displayed until scroll. RN 0.43 facebook/react-native#13316
• Carousel blank when changing tab for the first time. Will appear after first scroll. meliorence/react-native-snap-carousel#238

Problem:

Using this style which renders the whole list without the need to scroll it (applied on a really small list of 5 items):

optionsList: {
        maxHeight: 300
      },
      option: {
        container: {
          width: "100%",
          borderRadius: 8
        }
    }

...results in this issue shown below where the items above the initialScrollIndex are not rendered:

Screen.Recording.2023-11-23.at.11.28.45.mov

After applying the fix proposed in this PR:

Screen.Recording.2023-11-23.at.11.42.16.mov

This is without the maxHeight: mvs(300) so it works fine in all scenarios:

Screen.Recording.2023-11-23.at.11.44.14.mov

These changes align with SectionOptionsList:

• https://github.com/efstathiosntonas/react-native-select-pro/blob/780db33a4f7912f6a52205c7efac0819a5101e89/packages/react-native-select-pro/src/components/section-options-list/section-options-list.tsx#L71
• https://github.com/efstathiosntonas/react-native-select-pro/blob/780db33a4f7912f6a52205c7efac0819a5101e89/packages/react-native-select-pro/src/components/section-options-list/section-options-list.tsx#L37

[changeset-bot]

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[efstathiosntonas]

includes bonus fix for:

• Console warnings about initialScrollIndex "-1" is not valid #232
• [BUG] initialScrollIndex "-1" is not valid #214

[gitsad]

@efstathiosntonas thanks for your contribution!

[efstathiosntonas]

@gitsad anytime, keep it up!