Attempt at a small function for lxml parser that fix illformed xml when possible

fix.py

from lxml import etree as ET
import re


def fix_xml(xml_string: str) -> str:
    """ Given an illformated xml, try to fix it

    :param xml_string: XML that is faulty
    :return: xml that should not be faulty
    """
    parser = ET.XMLParser(recover=True)
    doc = ET.fromstring(xml_string, parser=parser)

    xml = None
    new_xml_string = ""+xml_string

    tag = re.compile(r"^Opening and ending tag mismatch: ([a-zA-Z\-_0-9]+) line ([0-9]+) and ([a-zA-Z\-_0-9]+), line ([0-9]+), column ([0-9]+)")
    while xml is None:
        try:
            xml = ET.fromstring(new_xml_string)
        except ET.XMLSyntaxError as E:
            # Find where the error is
            res = tag.findall(str(E))
            if res:
                tag1, line1, tag2, line2, col2 = res[0]

                # Chunk into lines
                lines = new_xml_string.split("\n")

                # Find the line of the first tag
                tag1_line_index = int(line1)-1
                tag1_line = lines[tag1_line_index]

                # Find the line of the second tag
                tag2_line_index = int(line2)-1
                tag2_line = lines[tag2_line_index]

                column = int(col2)

                if new_xml_string.count("<"+tag1) == new_xml_string.count("</"+tag1):
                    # Tag 1 is well closed, tag2 is not opened
                    tag2_line = tag2_line[:column-(len("</>")+len(tag2)+1)]+tag2_line[column-1:]
                    lines[tag2_line_index] = tag2_line
                else:
                    # Tag1 is not not closed, tag2 is well opened
                    tag_length = (len("</>")+len(tag2)+1)
                    # Insert the ending tag just before the ending tag
                    tag2_line = tag2_line[:column-tag_length]+"</"+tag1+">"+tag2_line[column-tag_length:]
                    lines[tag2_line_index] = tag2_line
                    pass
                if new_xml_string == "\n".join(lines):

                    raise E
                new_xml_string = "\n".join(lines)

            else:
                raise E
    print(new_xml_string)
    print("----")
    return new_xml_string


fix_xml("<fragment>"+""""
<lb n="1"/><name><expan><abbr>Sex</abbr><ex>to</ex></expan>Vervicio
<lb n="2"/>Modestino</name> et <name>Verv
<lb n="4"/>
... """+"</fragment>")
fix_xml("<fragment>"+""""
<lb n="2"/>Modestino</name> et <name>Verv
... """+"</fragment>")

fix_xml("<fragment>"+""""
Sex</abbr><ex>to</ex></expan>Vervicio
<lb n="2"/>Modestino</name> et <name>Verv
<lb break="no" n="3"/>iciae Modestinae</name>
<lb n="4"/>
... """+"</fragment>")