When running tl-setup in interactive text mode and giving an answer which is not correct, the prompt is shown once again until correct value is entered:
Server type [Master/agent]?c
Server type [Master/agent]?_
However when running tl-setup with an answer file, an invalid value will make tl-setup to choose the default value for the question. So if the above answer was given to server type prompt, master is selected and installed.
The problem get worse when the interactive text prompts supports shortening, eg. for the value agent, a user can write 'a' to selecting agent installation. When doing so in an answer file, the value is invalid and defaults will be used.
Expectations are that, if there is an invalid value given for a prompt in the answer file, the same logic should apply as when handling 'missing-values' either ask for a value or abort.