Fix: keep blank values as True to handle blank 'q' input.

[ahmad-alkadri]

This PR fixes (potentially) Issue #1050.

Location of the bug found at the function:

#app/filter.py

def extract_q(q_str: str, href: str) -> str:
    """Extracts the 'q' element from a result link. This is typically
    either the link to a result's website, or a string.

    Args:
        q_str: The result link to parse
        href: The full url to check for standalone 'q' elements first,
              rather than parsing the whole query string and then checking.

    Returns:
        str: The 'q' element of the link, or an empty string
    """

    return parse_qs(q_str)['q'][0] if ('&q=' in href or '?q=' in href) else ''

What happened when searching the query “Mathias Normann” (and potentially could be other queries) is that the href contains "q" but the value is blank in both href and q_str as follows:

# href:
"/search?safe=off&sca_esv=556514156&gbv=1&q=&si=ACFMAn9guiESjt..."

# q_str:
"safe=off&sca_esv=556514156&gbv=1&q=&si=ACFMAn9guiESjt..."

Thus, the value of ‘q’ would be blank.

By default, the function parse_qs will not keep the blank values nor keys, thus making the resulting parse_qs(q_str)['q'][0] throwing a KeyError because the key ‘q’ is simply not there.

To fix this, I simply put the keep_blank_values parameter of the parse_qs function into True. This fixes the problem.

Some screenshots:

Open to discussions and modifications if needed.