Fix onHover event not being triggered (#4297)

Fix onHover event not being triggered (#4297)

Fix onHover event not being triggered

The core controller was looking at the wrong object (options.hover) to
find the function to be called on hover. The function is provided on the
top level options object (options.onHover).

By using the helper function, there's no need to verify if the callback
is defined, as the helper already does that.

Fixes #4296