"""Converts a string representation of a fraction into a LaTeX formatted fraction.

This function takes a string that represents a fraction in the format 'a/b' and converts it into a LaTeX formatted fraction '\\frac{a}{b}'. The function handles cases where 'a' or 'b' contain the substring 'sqrt' by not attempting to convert them to integers. If the string does not contain exactly one '/', it is returned unchanged. If any conversion or assertion fails, the original string is returned.

Args:
    string (str): The string representation of the fraction to be converted.

Returns:
    str: The LaTeX formatted fraction if the input is a valid fraction, otherwise the original string.

Examples:
    >>> _fix_a_slash_b('1/2')
    '\\frac{1}{2}'
    >>> _fix_a_slash_b('sqrt/2')
    '\\frac{sqrt}{2}'
    >>> _fix_a_slash_b('1/sqrt')
    '\\frac{1}{sqrt}'
    >>> _fix_a_slash_b('sqrt/sqrt')
    '\\frac{sqrt}{sqrt}'
    >>> _fix_a_slash_b('0/0')
    '\\frac{0}{0}'
    >>> _fix_a_slash_b('0/sqrt')
    '\\frac{0}{sqrt}'
    >>> _fix_a_slash_b('47902/-174353981')
    '\\frac{47902}{-174353981}'
"""
You should write code starting with:
def _fix_a_slash_b(string: str) -> str:
    pass

