refactor: remove unnecessary return statements (#19625)

Author: koba04

packages/react-dom/src/events/plugins/SelectEventPlugin.js

@@ -215,8 +215,6 @@ function extractEvents(
  case 'keyup':
  constructSelectEvent(dispatchQueue, nativeEvent, nativeEventTarget);
  }
-
- return;
 }
 
 export {registerEvents, extractEvents};

packages/react-dom/src/events/plugins/SimpleEventPlugin.js

@@ -198,7 +198,6 @@ function extractEvents(
  accumulateTargetOnly,
  );
  }
- return event;
 }
 
 export {registerSimpleEvents as registerEvents, extractEvents};