fix: Error Cannot read properties of undefined (reading 'sendTelemetry')

[karlobencic]

If the database closes the connection during initialization, the app server continues to work with uninitialized properties.

[server]: Error during Data Source initialization: Connection lost: The server closed the connection.
QueryFailedError: Connection lost: The server closed the connection.
[server]: Flowise Server is listening at :3000
...
[server]: Error: Cannot read properties of undefined (reading 'sendTelemetry')
TypeError: Cannot read properties of undefined (reading 'sendTelemetry')

https://github.com/FlowiseAI/Flowise/blob/main/packages/server/src/index.ts#L82

Current code only checks for nodesPool initialization but there are still actions that can fail after the nodesPool is initialized. This PR addresses this issue by checking if the telemetry is successfully initialized as the last action in the initDatabase method. If it's not then the server should fail and be restarted.

[HenryHengZJ]

thanks @karlobencic !