As I alluded to in my original comment, you might not pick up on a transient error like an I/O error during testing. This is exactly the sort of thing a sensible default setting in the program should cover.

I'm sorry but error handling and testing requirements are true for any software or script a person writes. The application should not give a shit, and a simple execve() is the best way to go about it. It's the principle of least surprise, and people have had to keep in mind fork/exec semantics for decades.