fix(os): fix unavailable mapView on initialization

[mfazekas]

Fixes: https://github.com/rnmapbox/sponsors/issues/4

Repo, thanks much: @benjamin-sweney

import React, { useEffect, useRef } from 'react';
import { View } from 'react-native';
import { MapView } from '@rnmapbox/maps';

const Example = () => {
  const ref = useRef(null);

  useEffect(() => {
    const check = async () => {
      const center = await ref.current?.getCenter();

      console.log(center);
    };

    setTimeout(check, 1000);
  }, []);

  return (
    <View style={{ flex: 1, justifyContent: 'center' }}>
      <MapView
        ref={ref}
        zoomEnabled={false}
        scrollEnabled={false}
        scaleBarEnabled={false}
        style={{ height: 400 }}
      />
    </View>
  );
};

export default Example;