File encoding issue with chardet library. A few characters '{', '}', '~' with several combinations will cause chardet to fail. Find out who are the bad guys!! For fancy looks, I used colorclass and terminaltables.

failure_chars_detection.py

#!/usr/bin/env python3
import chardet
from colorclass import Color
from terminaltables import AsciiTable


def generate_test(chars_list):
    table_data = [['Chars', 'Confidence', 'Encoding', 'Issue'], ]
    for chars in chars_list:
        result = chardet.detect(chars.encode('utf-8'))
        conf, enco = result['confidence'], result['encoding']
        if not conf or not enco:
            table_data.append(
                [chars, str(conf), 'None', Color('{red}x{/red}')]
            )
        else:
            table_data.append(
                [chars, str(conf), enco, Color('{green}✔{/green}')]
            )
    table = AsciiTable(sorted(table_data, key=lambda x: x[3], reverse=True))
    print(table.table)


def generate_chars_list(chars):
    chars_set = set()
    def permutation(vals, curt):
        chars_set.add(''.join(curt))
        for i, v in enumerate(vals):
            permutation(vals[:i] + vals[i + 1:], curt + [v])
    permutation(list(chars), [])
    return list(chars_set)

if __name__ == '__main__':
    chars_list = generate_chars_list('{}~')
    generate_test(chars_list)
    

"""
+-------+------------+----------+-------+
| Chars | Confidence | Encoding | Issue |
+-------+------------+----------+-------+
| {     | 1.0        | ascii    | ✔     |
| {~}   | 1.0        | ascii    | ✔     |
| {}~   | 1.0        | ascii    | ✔     |
| }     | 1.0        | ascii    | ✔     |
| ~}{   | 1.0        | ascii    | ✔     |
| {}    | 1.0        | ascii    | ✔     |
| ~}    | 1.0        | ascii    | ✔     |
| }{~   | 1.0        | ascii    | ✔     |
| {~    | 1.0        | ascii    | ✔     |
| }{    | 1.0        | ascii    | ✔     |
| ~     | 1.0        | ascii    | ✔     |
| }~    | 1.0        | ascii    | ✔     |
|       | 0.0        | None     | x     |
| }~{   | 0.0        | None     | x     |
| ~{}   | 0.0        | None     | x     |
| ~{    | 0.0        | None     | x     |
+-------+------------+----------+-------+
"""