No inputs directory. This is a self-contained task. Here is my solution.

```python
def int_to_roman(n):
    if not isinstance(n, int) or isinstance(n, bool):
        raise ValueError("input must be an integer")
    if n < 1 or n > 3999:
        raise ValueError("integer out of range 1..3999")
    table = (
        (1000, "M"), (900, "CM"), (500, "D"), (400, "CD"),
        (100, "C"), (90, "XC"), (50, "L"), (40, "XL"),
        (10, "X"), (9, "IX"), (5, "V"), (4, "IV"), (1, "I"),
    )
    result = []
    for value, symbol in table:
        count, n = divmod(n, value)
        result.append(symbol * count)
    return "".join(result)


def roman_to_int(s):
    if not isinstance(s, str):
        raise ValueError("input must be a string")
    if s == "":
        raise ValueError("empty string is not a valid Roman numeral")
    table = (
        (1000, "M"), (900, "CM"), (500, "D"), (400, "CD"),
        (100, "C"), (90, "XC"), (50, "L"), (40, "XL"),
        (10, "X"), (9, "IX"), (5, "V"), (4, "IV"), (1, "I"),
    )
    if any(ch not in "IVXLCDM" for ch in s):
        raise ValueError("invalid characters in Roman numeral")
    total = 0
    i = 0
    for value, symbol in table:
        while s.startswith(symbol, i):
            total += value
            i += len(symbol)
    if i != len(s):
        raise ValueError("malformed or non-canonical Roman numeral")
    if total < 1 or total > 3999:
        raise ValueError("value out of range 1..3999")
    if int_to_roman(total) != s:
        raise ValueError("non-canonical Roman numeral")
    return total
```