Probot version 7.2 is not starting my app - github

Question

With probot 7.2, if I create a simple index.js like
module.exports = app => {
app.log('YYYYYYYEEEEEEEEEEEAAAAAAAAAAAHHHHHHHHH it is working!!!!')
}
This export is not working, as when I run the application, I never see my log message. The npm run dev give those log:
> test#1.0.0 dev /tmp/test
> nodemon
[nodemon] 1.18.4
[nodemon] to restart at any time, enter `rs`
[nodemon] watching: .env *.*
[nodemon] starting `npm start`
> test#1.0.0 start /tmp/test
> probot run ./index.js
08:46:15.243Z INFO probot: Listening on http://localhost:3000
08:46:15.817Z INFO probot:
Welcome to Probot! Go to http://localhost:3000 to get started.
If I downgrade the version to 7.1 it is fine.
Is someone know if there is some (and which) change to do with 7.2 version ?

Answer 1

Just found out why, so I answer myself:
On 7.1 version, there is error when your start probot without the needed env variable.
On 7.2 those errors are not showing. You need to have env variable correctly set else it will simply start but silently fail to load your setup.
The env (or .env file) must define:
APP_ID=...
WEBHOOK_PROXY_URL=...
LOG_LEVEL=...
WEBHOOK_SECRET=...
PRIVATE_KEY=...
The complete possible env variables are defined in the documentation