The froghemoth has both lightning resistance and Shock Susceptibility; is this an error? Are there other monsters like this?

In Volo’s Guide to Monsters, the Froghemoth (pg. 145) has resistance to lightning damage, but also has the Shock Susceptibility trait, which gives it various penalties whenever it takes lightning damage.

I find this hard to wrap my mind around from a creature biology standpoint, as well as from a gameplay point of view. Is this a mistake? Is there any precedent for a monster having this dual resistance and vulnerability?