I can confirm same issue for me.
Interestingly, https://api.chess.com/pub/player/erik/games/2010/04 does work. Also one of my links works as well, https://api.chess.com/pub/player/djcaf/games/2010/04
Certainly a strange issue and rather cryptic error.
Although
https://api.chess.com/pub/player/erik/games/archives
tells me what game archives are available for a user,
but all the links i.e.
https://api.chess.com/pub/player/erik/games/2009/10
return with the same message:
{"message":"'Chess\\WebBundle\\Doctrine\\ORM\\Internal\\Hydration\\GameLiveHydrator' is an invalid hydration mode.","code":0}
Examples from page https://www.chess.com/news/view/published-data-api