I have flown to Easter island (IPC) a couple of times in the last few years. As has already mentioned the planning rules usually allow for something called "Island Reserves" (2 hours holding fuel) to be substituted when an adequate alternate cannot be provided due to the remoteness of the destination.
On both occaissions I flew there, the relatively light payload allowed for a return to the departure airfield or a diversion to another remote alternate, however that was not a planning requirement.
Everything on Easter Island is expensive due to the transportation logistics and fuel is most certainly no exception. It is eyewateringly expensive. For that reason alone most Commercial Air Transport flights would be tankering as much fuel inbound as possible. However that aside, the flight planning rules outlined above, would normally enable the flight to be undertaken.