Await the creation of the xlsx stream writer

Author: toddkazakov

lib/handlers/userDataHandler.js

@@ -76,7 +76,7 @@ export default function userDataHandler() {
           .pipe(res);
       } else {
         res.attachment('TidepoolExport.xlsx');
-        writeStream = dataTools.xlsxStreamWriter(res, processorConfig);
+        writeStream = await dataTools.xlsxStreamWriter(res, processorConfig);
 
         dataResponse.data
           .pipe(dataTools.jsonParser())