Default prior on intercept when using offset

[fweber144]

Initially, I thought it might be good to post this issue in the Stan Forums, but it seems like it is too specific there. So perhaps this GitHub issue tracker is a better place, although I'm still not sure if its really a bug or if I am just misunderstanding something.

[paul-buerkner]

I am not sure I would call it a bug. Rather, the default prior on the intercept is not elaborate enough yet to take the offset into account. I cannot provide any guarantee that the brms default priors are sensible in all cases. It is up to the user to specify appropriate priors. That said, I think it should not be too difficult to adjust the default priors on the intercept according to the offset, so this may be implemented at some point.

[paul-buerkner]

This should now be implmented.