Erratum: Hard photoproduction of a diphoton with a large invariant mass [Phys. Rev. D 96, 074008 (2017)]

We correct the expression for the $\ensuremath{\gamma}N\ensuremath{\rightarrow}\ensuremath{\gamma}\ensuremath{\gamma}{N}^{\ensuremath{'}}$ amplitude in the generalized Bjorken regime, where the diphoton is nearly forward and its invariant mass is the hard scale enabling to factorize the scattering amplitude in terms of generalized parton distributions. This amplitude has a very peculiar and interesting analytic structure, while the cross section estimates are only slightly changed.