I don't see an error amp section offhand.
It looks like the schematics were captured from PCB layout? So no very readable. I could sit and stare a while, but you might prefer showing what part of the circuit you're actually asking about, what components are involved, and to redraw the section for better readability. (You may even answer your own question in the process!)
I will say something general about these sorts of modern supplies; where there's an error amp into an opto, and the opto is more or less direct-driving the primary-side controller, and the controller input is a cascode type pin, and it's probably LLC resonant topology; then, the RC at the error amp probably compensates the opto's dominant pole (which is rather low because of low bias current and the already low bandwidth of the phototransistor) and the controller transfer function is basically type 1; regulation (especially transient response) is still good because the "plant" itself responds quickly (say, within a cycle). This actually makes the output capacitance determined by opto pole, since the controller/plant can't respond any faster than that, and the capacitance takes over at shorter time scales (< ~1ms).
Tim