  Naive light-front quantization, carried out by a light-front energy
integration of covariant amplitudes, is not guaranteed to generate the
corresponding Feynman amplitudes. In an explicit example we show that the
nonvalence contribution to the minus-component of the EM current of a meson
with fermion constituents has a persistent end-point singularity. Only after
this term is subtracted, the result is covariant and satisfies current
conservation. If the spin-1/2 constituents are replaced by spin zero ones, the
singularity does not occur and the result is, without any adjustment, identical
to the Feynman amplitude. Numerical estimates of valence and nonvalence
contributions are presented for the cases of fermion and boson constituents.
