I'm testing an example of the library with the version "4.0.0-beta.3" (https://github.com/uber/react-map-gl), but I have this warning to method onViewportChange:
Warning: Cannot update during an existing state transition (such as within render). Render methods should be a pure function of props and state.
Solved issue: Version 4.0.0-beta.4 https://github.com/uber/react-map-gl/issues/642