VIDEO : Director On 'Last Jedi' Explains Rey?s Cave Vision

Warning: spoilers for The Last Jedi.
Star Wars: The Last Jedi raised some major questions about the potential of evil within its lead characters, especially Daisy Ridley's Rey.
Rey has a vision of a dark place on Ahch-To.
Luke Skywalker tells Rey that she has a strong connection to the dark side. Does that mean she will turn to evil in future movies?
Director Rian Johnson is opening up about Rey?s vision in that dark place on Ahch-To.
Simply put every place of light has a reflective place of darkness. If the Jedi temple is a place of light the area below it is the place of darkness.