message: check if resolve_field returns nullptr in remove builder
  Summary: If it does, let it fall through to later checks
diff: @@ -633,7 +633,7 @@ bool params_change_regs(DexMethod* method) {
  if (opcode::is_an_iget(op)) {
  DexField* field =
  resolve_field(insn->get_field(), FieldSearch::Instance);
  - if (field->get_class() == arg) {
  + if (field && field->get_class() == arg) {
  continue;
  }
  }
  