PVS-Studio warning V612 for TPP

const char* ResidueMass::getStdModResidues(....) {
  ....
  for (rmap::const_iterator i = p.first; i != p.second; ++i) {
    const cResidue &r = (*i).second;
    if (r.m_masses[0].m_nterm) {
        n_term_aa_mod = true;
    } else if (r.m_masses[0].m_cterm) {
        c_term_aa_mod = true;
    }
    return r.m_residue.c_str();
  }

  if(! strcmp(mod, "+N-formyl-met (Protein)")) {
    return "n";
  } if (! strcmp(mod, "13C6-15N2 (K)")) {
    return "K";
  } if (! strcmp(mod, "13C6-15N4 (R)")) {
    return "R";
  ....
}

This suspicious code was found in TPP project by PVS-Studio static code analyzer.
Warning message is:
V612 An unconditional 'return' within a loop. residuemass.cxx 1442

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