Fix assert

NETWORK_ERROR is usually an AggregateError which causes an
assert in BoxError

src/dns/namecheap.js

@@ -61,7 +61,7 @@ async function getZone(domainConfig, zoneName) {
     query.TLD = zoneName.slice(query.SLD.length + 1);
 
     const [error, response] = await safe(superagent.get(ENDPOINT).query(query).ok(() => true));
-    if (error) throw new BoxError(BoxError.NETWORK_ERROR, error.message);
+    if (error) throw new BoxError(BoxError.NETWORK_ERROR, error);
 
     const parser = new xml2js.Parser();
     const [parserError, result] = await safe(util.promisify(parser.parseString)(response.text));