make logger optional so code can be re-used for CLI interface

lib/services/dom-parser.js

@@ -37,11 +37,14 @@ const createLocationData = (streetText, areaText) => {
 // NOTE: Fallback parser
 // Attempt reading event data directly from DOM
 const parseUsingDOM = (html, url, { logger }) => {
-  logger.log({
-    message: 'Using fallback DOM parser',
-    level: 'info',
-    service: 'parser',
-  })
+  if (logger) {
+    logger.log({
+      message: 'Using fallback DOM parser',
+      level: 'info',
+      service: 'parser',
+    })
+  }
+
   const $ = cheerio.load(html)
   const title = $('title').text()