I can visualize many beginners doing this as a first en.wikipedia.org/.../Hello_world_program the poor sods are not going to get an error message, the code will just hang.
I know why, but consider it bad that you get a hang, not an error message, especially when you feebly try do run Keil for the first time. Yes Please read the manual should cover it, but did you Please read the manual the first time you started C?
Erik