The electromagnetic field configuration does contribute energy/momentum. In general, every field that interacts with the election field contributes: an “electro

The electromagnetic field configuration does contribute energy/momentum. In general, every field that interacts with the election field contributes: an “electron” stands for a complicated joint excitation of the electron, photon, W/Z boson, quark, gluon, ... quantum fields and what we call the momentum/energy of the electron is just the total of that of all of these fields.