Looking at the error code that you get "Uncaught TypeError: Cannot read property 'setVelocityX' of undefined" and your implementation of the update function (from the screenshot), the variable "player" is undefined when you call the update function, so an error is thrown and it is only called once.
I don't know where "player" is supposed to be defined based on the code you've shared, so I can't tell much else. This could be an issue with how you set up your interpreter or your implementation of update.
~ Monica