fix(appointment-helper): fix query for finding next appointment (#180)

(cherry picked from commit b3c88fc)

Author: Sebastian

src/app/helper/appointment.js

@@ -71,22 +71,29 @@ appointmentHelper.notify = () => new Promise(async (resolve) => {
   const now = moment.tz(settings.appointmentsTimezone);
 
   let nextAppointment = await Appointment
-    .findOne({
+    .find({
       user: { $exists: true, $ne: null },
       weekDay: now.weekday(),
       hour: {
         $gte: now.hours() * 100 + now.minutes(),
       }
     })
+    .sort({
+      hour: 'asc'
+    })
+    .limit(1)
     .populate('user', 'name gravatarHash')
+    .lean()
     .then();
 
 
-  if (!nextAppointment) {
+  if (!nextAppointment || nextAppointment.length < 1) {
     resolve('No appointment found. Aborting.');
     return;
   }
 
+  nextAppointment = nextAppointment[0];
+
   if (settings.appointmentsIncrement) {
     // add global increment
     nextAppointment = appointmentHelper.addIncrement(nextAppointment, settings.appointmentsIncrement);