Error: invalid use of 'void' - ArduinoOTA on ESP8266

Ahhhh, I missed the attempt at chaining. That's another thing (besides the use of Lambda expressions) that makes this code difficult to read and maintain.

I'd get rid of the chaining and break it out into separate method calls.

Then, get rid of the Lambdas and provide pointers to explicitly defined functions.

I mean, come on, this looks like initialization code. Does it really provide any required optimization in exchange for making it hard to read? Beware of false economies.