undefined is not an object (evaluating 'RNGestureHandlerModule.State'

1. remove node_modules and package-lock.json
2. npm install
3. npm install --save react-navigation
4. npm install --save react-native-gesture-handler
5. react-native link

If you are using react-link to link your dependencies:

1. 0pen your ios Podfile and delete all yout linked dependencies: pod 'xxxxxxx', :path => '../node_modules/xxxxx
2. Close Xcode
3. In your /ios folder run "pod update"
4. In your project source run "react-native link"
5. Open Xcode and Clean Build Folder from Xcode Menu -> Product
6. Run your application from Xcode
7. Link manually the dependency "react-native-gesture-handler" into your Xcode Project following steps in documentation: https://facebook.github.io/react-native/docs/linking-libraries-ios
8. Now run your application from Xcode, you should be fine.