Is xml2js guaranteed to be synchronous and does it throw errors?

I am using xml2js and I need to be robust since there is no guarantee that the source of the xml is well-formed. So, I need to ensure that all errors are able to be handled. If the code looks something like this:

let parseString = require('xml2js').parseString;
let xml = getTheXml(...);
parseString(xml, (err, result) => {
    if (err) { handleError(err) }
    else { handleResult(result); }
});

Am I guaranteed that parseString will never throw an error and that all errors are passed through as an err object to the callback?

Or to be safer, do I need to do the following:

let parseString = require('xml2js').parseString;
let xml = getTheXml(...);
try {
  parseString(xml, (err, result) => {
    if (err) { handleError(err) }
    else { handleResult(result); }
  });
} catch (err) { handleError(err); }

Furthermore, am I guaranteed that parseString executes synchronously?

via Andrew Eisenberg