Remove 6 $FlowFixMe[sketchy-null-*] suppressions (Button, URL, ScrollView, RNTester) (#59211)

Summary:
Pull Request resolved: #59211

Replaces six `$FlowFixMe[sketchy-null-string|bool|number]` suppressions with explicit checks that keep the exact runtime behavior, including for `''`, `0` and `NaN`.

- `Button`: `ariaLabel || accessibilityLabel` became `ariaLabel != null && ariaLabel !== '' ? ariaLabel : accessibilityLabel`, so an empty `aria-label` still falls back to `accessibilityLabel`.
- `URL`: in the constructor, `!base` became `base == null || base === ''`. A `URL` instance is always truthy, so this matches the old check.
- `ScrollView` (2): `keyboardShouldPersistTaps` is typed `?('always' | 'never' | 'handled')`, whose values are never falsy. So `!keyboardShouldPersistTaps` is the same as `keyboardShouldPersistTaps == null`.
- RNTester `PressableExample`: `setForce(event.nativeEvent?.force || 1)` became `touchForce != null && Boolean(touchForce) ? touchForce : 1`, reading the value into a local const. `Boolean()` keeps the `0`/`NaN` fallback exactly as `||` did, and `!= null` lets Flow refine the value to `number`.
- RNTester `useJsStalls`: `!state.stallIntervalId` became `!Boolean(state.stallIntervalId)`. The interval ID is an opaque `IntervalID` in the OSS Flow libdefs, so it can't be compared with `0`; `Boolean()` keeps the exact semantics.

No new suppressions, casts, comments, or tests.

Changelog: [Internal]

Reviewed By: christophpurrer

Differential Revision: D126162944

fbshipit-source-id: d0402e37351005d364a45c90d3bb086953179242

Author: jcperez-ch

packages/react-native/Libraries/Blob/URL.js

@@ -81,8 +81,7 @@ export class URL {
   // $FlowFixMe[missing-local-annot]
   constructor(url: string, base?: string | URL) {
     let baseUrl = null;
-    // $FlowFixMe[sketchy-null-string]
-    if (!base || validateBaseUrl(url)) {
+    if (base == null || base === '' || validateBaseUrl(url)) {
       this._url = url;
       if (this._url.includes('#')) {
         const split = this._url.split('#');

packages/react-native/Libraries/Components/Button.js

@@ -271,8 +271,7 @@ const Button: component(
       accessibilityActions={accessibilityActions}
       onAccessibilityAction={onAccessibilityAction}
       accessibilityLabel={
-        // $FlowFixMe[sketchy-null-string]
-        ariaLabel || accessibilityLabel
+        ariaLabel != null && ariaLabel !== '' ? ariaLabel : accessibilityLabel
       }
       accessibilityHint={accessibilityHint}
       accessibilityLanguage={accessibilityLanguage}

packages/react-native/Libraries/Components/ScrollView/ScrollView.js

@@ -1586,8 +1586,8 @@ class ScrollView extends React.Component<ScrollViewProps, ScrollViewState> {
       // then the second tap goes to the actual interior view)
       const {keyboardShouldPersistTaps} = this.props;
       const keyboardNeverPersistTaps =
-        // $FlowFixMe[sketchy-null-bool]
-        !keyboardShouldPersistTaps || keyboardShouldPersistTaps === 'never';
+        keyboardShouldPersistTaps == null ||
+        keyboardShouldPersistTaps === 'never';
 
       if (typeof e.target === 'number') {
         if (__DEV__) {
@@ -1669,8 +1669,8 @@ class ScrollView extends React.Component<ScrollViewProps, ScrollViewState> {
 
     const {keyboardShouldPersistTaps} = this.props;
     const keyboardNeverPersistsTaps =
-      // $FlowFixMe[sketchy-null-bool]
-      !keyboardShouldPersistTaps || keyboardShouldPersistTaps === 'never';
+      keyboardShouldPersistTaps == null ||
+      keyboardShouldPersistTaps === 'never';
 
     // Dismiss the keyboard now if we didn't become responder in capture phase
     // to eat presses, but still want to dismiss on interaction.

packages/rn-tester/js/examples/Pressable/PressableExample.js

@@ -191,8 +191,12 @@ function ForceTouchExample() {
           style={styles.wrapper}
           testID="pressable_3dtouch_button"
           onStartShouldSetResponder={() => true}
-          // $FlowFixMe[sketchy-null-number]
-          onResponderMove={event => setForce(event.nativeEvent?.force || 1)}
+          onResponderMove={event => {
+            const touchForce = event.nativeEvent?.force;
+            setForce(
+              touchForce != null && Boolean(touchForce) ? touchForce : 1,
+            );
+          }}
           onResponderRelease={event => setForce(0)}>
           <Text style={styles.button}>Press Me</Text>
         </View>

packages/rn-tester/js/utils/useJsStalls.js

@@ -67,8 +67,7 @@ const useJsStalls = (): ({
       onStall: ({busyTime}) =>
         setStallsState(state => {
           // If previous interval was cleared
-          // $FlowFixMe[sketchy-null-number]
-          if (!state.stallIntervalId) {
+          if (!Boolean(state.stallIntervalId)) {
             return state;
           }