Earlier quoted context omitted.
What language makes it impossible to write if parse(config) == false then reboot?
Impossible is a big word :). But while a C or C++ program tends to crash in the presence of an error, like with a segfault, a lot of languages just throw an error which you can catch. So you could proceed with the default values, if the file cannot be read correctly.
C and C++ programs tend to crash in the presence of an error, but so do rust programs (panic), C# and java and js and python programs (unhandled exception). Some languages make it harder to footgun yourself for certain types of errors, but never all types of errors.
I have seen js programs (and similar stuff in other languages) crash because of something like
JSON.parse(response).list[0].string.length
Does rust protect from such mistakes (because I know some people on here like to claim rust is the answer to everything)? Verbatim from their docs:
let v = vec![0, 2, 4, 6];
println!("{}", v[6]); // it will panic!
I have written such code myself because I was lazy or distracted or "need performance" or "this can never be empty per spec" or "oops, my range calculation was off by one", tho luckily I didn't outright brick anything, yet.