Program: 133281
Project: 133281
Buggy source:
static BigInteger decode(String cypher_string) throws DecodeException {
  int[] codeword=new int[ReedSolomon.initial_codeword.length];
  System.arraycopy(ReedSolomon.initial_codeword,0,codeword,0,ReedSolomon.initial_codeword.length);
  int codeword_length=0;
  for (int i=0; i < cypher_string.length(); i++) {
    int position_in_alphabet=ReedSolomon.alphabet.indexOf(cypher_string.charAt(i));
    if (position_in_alphabet <= -1 || position_in_alphabet > ReedSolomon.alphabet.length()) {
      continue;
    }
    if (codeword_length > 16) {
      throw new CodewordTooLongException();
    }
    int codework_index=ReedSolomon.codeword_map[codeword_length];
    codeword[codework_index]=position_in_alphabet;
    codeword_length+=1;
  }
  if (codeword_length == 17 && !ReedSolomon.is_codeword_valid(codeword) || codeword_length != 17) {
    throw new CodewordInvalidException();
  }
  int length=ReedSolomon.base_32_length;
  int[] cypher_string_32=new int[length];
  for (int i=0; i < length; i++) {
    cypher_string_32[i]=codeword[length - i - 1];
  }
  StringBuilder plain_string_builder=new StringBuilder();
  do {
    int new_length=0;
    int digit_10=0;
    for (int i=0; i < length; i++) {
      digit_10=digit_10 * 32 + cypher_string_32[i];
      if (digit_10 >= 10) {
        cypher_string_32[new_length]=digit_10 / 10;
        digit_10%=10;
        new_length+=1;
      }
 else       if (new_length > 0) {
        cypher_string_32[new_length]=0;
        new_length+=1;
      }
    }
    length=new_length;
    plain_string_builder.append((char)(digit_10 + (int)'0'));
  }
 while (length > 0);
  return new BigInteger(plain_string_builder.reverse().toString());
}

Fixed version (ground truth):
public static BigInteger decode(String cypher_string) throws DecodeException {
  int[] codeword=new int[ReedSolomon.initial_codeword.length];
  System.arraycopy(ReedSolomon.initial_codeword,0,codeword,0,ReedSolomon.initial_codeword.length);
  int codeword_length=0;
  for (int i=0; i < cypher_string.length(); i++) {
    int position_in_alphabet=ReedSolomon.alphabet.indexOf(cypher_string.charAt(i));
    if (position_in_alphabet <= -1 || position_in_alphabet > ReedSolomon.alphabet.length()) {
      continue;
    }
    if (codeword_length > 16) {
      throw new CodewordTooLongException();
    }
    int codework_index=ReedSolomon.codeword_map[codeword_length];
    codeword[codework_index]=position_in_alphabet;
    codeword_length+=1;
  }
  if (codeword_length == 17 && !ReedSolomon.is_codeword_valid(codeword) || codeword_length != 17) {
    throw new CodewordInvalidException();
  }
  int length=ReedSolomon.base_32_length;
  int[] cypher_string_32=new int[length];
  for (int i=0; i < length; i++) {
    cypher_string_32[i]=codeword[length - i - 1];
  }
  StringBuilder plain_string_builder=new StringBuilder();
  do {
    int new_length=0;
    int digit_10=0;
    for (int i=0; i < length; i++) {
      digit_10=digit_10 * 32 + cypher_string_32[i];
      if (digit_10 >= 10) {
        cypher_string_32[new_length]=digit_10 / 10;
        digit_10%=10;
        new_length+=1;
      }
 else       if (new_length > 0) {
        cypher_string_32[new_length]=0;
        new_length+=1;
      }
    }
    length=new_length;
    plain_string_builder.append((char)(digit_10 + (int)'0'));
  }
 while (length > 0);
  return new BigInteger(plain_string_builder.reverse().toString());
}