ValueError: reached end of bitarray

Question

I am building a compression algorithm that takes a tab-delimited file, converts each column to binary (bitarray) using huffman coding, then converts the bitarray to hexadecimal format (ba2hex). This is using the bitarray library. I am getting the error ValueError: reached end of bitarray at the line: iter = str("\t".join(canonical_decode(binary, count, symbol))) in the decode function. My code works for many lines of the file, but not all.

Any help sorting out the reason for this error would be greatly appreciated.

def encode(stringMap):
    with open (test_dir_path + "compressed.txt", 'w') as compressed_file:
        for key in stringMap:
            list = stringMap[key]
            # print(list)
            dict = totalHuffmanDict[key]
            s = ""
            for string in list:
                binary = dict[string]
                s += binary
            s += "\n"
            b = bitarray(s)
            b.fill()
            hex = ba2hex(b)
            compressed_file.write(hex)
            compressed_file.write("\n")

listOfLists = []
def decode(count, symbol, key):
    with open (test_dir_path + "compressed.txt", "r") as compressed_file:
        lineNum = 0
        key = int(key)
        for line in compressed_file:
            lineNum = lineNum + 1
            
            if lineNum == key:
                binary = hex2ba(line.strip())
                iter = str("\t".join(canonical_decode(binary, count, symbol)))
                list = iter.split("\t")
                list = list[0:NUM_LINES]
                listOfLists.append(list)