Thanks swiftyspiffy.
I changed the settings in my application and got the twitch popup ‘allow access’ etc.
However I get the following:
InternalOAuthError: Failed to obtain access token
at OAuth2Strategy._createOAuthError (/Users/franceswarburton/myapp1/node_modules/passport-oauth2/lib/strategy.js:379:17)
at /Users/franceswarburton/myapp1/node_modules/passport-oauth2/lib/strategy.js:166:45
at /Users/franceswarburton/myapp1/node_modules/oauth/lib/oauth2.js:191:18
at passBackControl (/Users/franceswarburton/myapp1/node_modules/oauth/lib/oauth2.js:132:9)
at IncomingMessage. (/Users/franceswarburton/myapp1/node_modules/oauth/lib/oauth2.js:157:7)
at IncomingMessage.emit (events.js:165:20)
at endReadableNT (_stream_readable.js:1101:12)
at process._tickCallback (internal/process/next_tick.js:152:19)
The only thing I’m not clear on is 
const SESSION_SECRET = ‘TEST123’;
I see in the Twitch settings I see client secret and a button to create a new.
Is this what I create or do I find this somewhere ?
Is this the issue now ?
The docs are not really clear from a beginners point of view.
Cheers
Steve Warby