Error in route in walking

Directions API
1

There is an error in this route

https://graphhopper.com/maps/?point=James%20I%20University%2C%2012071%2C%20Castellón%20de%20la%20Plana%2C%20Spain&point=Barcelona%2C%20Spain&locale=en&vehicle=foot&weighting=fastest&elevation=true&use_miles=false&layer=Omniscale

2

“Error” in which sense? It is faster compared to a route on the mainland.

3

The walking route goes over the sea. It’s not possible to walk over sea.

4

That is a ferry route.