proc_lambda(mrb_state *mrb, mrb_value self)
{
  mrb_value blk;
  struct RProc *p;

  mrb_get_args(mrb, "&", &blk);
  if (mrb_nil_p(blk)) {
    mrb_raise(mrb, E_ARGUMENT_ERROR, "tried to create Proc object without a block");
  }
  if (!mrb_proc_p(blk)) {
    mrb_raise(mrb, E_ARGUMENT_ERROR, "not a proc");
  }
  p = mrb_proc_ptr(blk);
  if (!MRB_PROC_STRICT_P(p)) {
    struct RProc *p2 = MRB_OBJ_ALLOC(mrb, MRB_TT_PROC, p->c);
    mrb_proc_copy(mrb, p2, p);
    p2->flags |= MRB_PROC_STRICT;
    return mrb_obj_value(p2);
  }
  return blk;
}
A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit.