static unsigned HuffmanTree_makeFromFrequencies(HuffmanTree* tree, const unsigned* frequencies,
                                                size_t mincodes, size_t numcodes, unsigned maxbitlen)
{
	unsigned* lengths;
  unsigned error = 0;
  while(!frequencies[numcodes - 1] && numcodes > mincodes) numcodes--; /*trim zeroes*/
  tree->maxbitlen = maxbitlen;
  tree->numcodes = (unsigned)numcodes; /*number of symbols*/
  lengths = (unsigned*)realloc(tree->lengths, numcodes * sizeof(unsigned));
	if (!lengths)
		free(tree->lengths);
	tree->lengths = lengths;
  if(!tree->lengths) return 83; /*alloc fail*/
  /*initialize all lengths to 0*/
  memset(tree->lengths, 0, numcodes * sizeof(unsigned));

  error = lodepng_huffman_code_lengths(tree->lengths, frequencies, numcodes, maxbitlen);
  if(!error) error = HuffmanTree_makeFromLengths2(tree);
  return error;
}
The software does not check the return value from a method or function, which can prevent it from detecting unexpected states and conditions.