Straight to the point, I faced the following react native error when I ran one of my react native project.
GestureHandler already initialized for root view com.swmansion.gesturehandler.react.RNGestureHandlerEnabledRootView{736d100 V.E…… …….D0,0-1080, 1962 #29}

Yes, the error is related with react native gesture handler library I used in association with react navigation library. React native gesture handler is the library which manages gestures for navigation actions of react navigation library.
So, what’s the solution for this react native error?
It’s pretty simple. Just restart your metro bundler and rerun the project with react-native run-android or react-native run-ios. That’s it, the error would be gone.