fix reading credentials

lib/googlecalendar.ts

@@ -1,14 +1,20 @@
 import { google } from 'googleapis'
 import { Booking } from '../db/booking'
 
-const keyFile = process.env.GOOGLE_SERVICE_ACCOUNT_KEY_FILE
 const calendarId = process.env.GOOGLE_CALENDAR_ID
+let credentials
+
+try {
+  credentials = JSON.parse(process.env.GOOGLE_SERVICE_ACCOUNT_KEY_JSON);
+} catch (error) {
+  console.error('Unable to parse process.env.GOOGLE_SERVICE_ACCOUNT_KEY_JSON - invalid JSON?');
+  throw error;
+}
 
 const auth = new google.auth.GoogleAuth({
-  keyFile,
+  credentials,
   scopes: [
     'https://www.googleapis.com/auth/calendar',
-    'https://www.googleapis.com/auth/calendar.readonly',
   ],
 })
 
@@ -39,8 +45,9 @@ function getSummary(booking: Partial<Booking>): string {
 }
 
 export async function createCalendarEvent(booking: Booking): Promise<Booking> {
+  const authInstance = await auth.getClient();
   const response = await calendar.events.insert({
-    auth,
+    auth: authInstance,
     calendarId,
     requestBody: {
       summary: getSummary(booking),