parseString() missing error management

[AndreaFranchini]

Hi,
I was trying to open a PR but i have trouble with permissions.

In some cases xml2js.Parser parseString() can throw an error after execute the callback.

This leads to the emission of a node 'uncaughtException' in the express application.

Following lines (index.js 32-40)

parser.parseString(req.body, function(err, xml) {
    if(err) {
        err.status = 400;
        return next(err);
    }

    req.body = xml || req.body;
    next();
});

Should be wrapped

try {
    parser.parseString(req.body, function(err, xml) {
        if(err) {
            err.status = 400;
            return next(err);
        }
    
        req.body = xml || req.body;
        next();
    });
} catch (err) {
    // in some cases xml2js.Parser parseString() can
    // throw an error after execute the callback
    // see it source code for more details
}

[fiznool]

Fixed in v2.0.0