Handle missing mutation names in LoggerScheduledMutator::post_exec, at /crates/libafl/scheduled.rs

[Jay-1409]

Description

Previously, LoggerScheduledMutator::post_exec used .unwrap() when retrieving mutation names from the scheduled mutator. This could cause a panic if a mutation index had no corresponding name.

This PR replaces the unwrap() with proper error handling, returning an Error if a mutation name is missing. This ensures post_exec fails gracefully instead of panicking, improving stability during fuzzing sessions.

Also added tests

Checklist

• I have run ./scripts/precommit.sh and addressed all comments

[domenukk]

Can we somehow get the actual mutation and debug print that?

[Jay-1409]

I believe that if we store the name over here then its possible to print the name as well. Shoud i proceed?

Line 363 scheduled.rs

    fn scheduled_mutate(&mut self, state: &mut S, input: &mut I) -> Result<MutationResult, Error> {
        let mut r = MutationResult::Skipped;
        let num = self.iterations(state, input);
        self.mutation_log.clear();
        for _ in 0..num {
            let idx = self.schedule(state, input);
            self.mutation_log.push(idx); //<---------- here save the name as well ?
            let outcome = self.mutations_mut().get_and_mutate(idx, state, input)?;
            if outcome == MutationResult::Mutated {
                r = MutationResult::Mutated;
            }
        }
        Ok(r)
    }

[domenukk]

if it's possible to only store a ref (not clone the full string), then yes, but I highly doubt it.

[Jay-1409]

if it's possible to only store a ref (not clone the full string), then yes, but I highly doubt it.

I cannot think of a way to implement that without saving the entire string.

Could you suggest some ideas to me?

Otherwise, could we proceed without that specific change? Further if I do figure it out, I'll propose it with a new pr

[domenukk]

Can we get the actual mutation in the error message and include the debug representation? Not using name at all? In the error handler we have a lot of time, it's not a hot code path.
If not I can merge the current state, too, but it'll make debugging this harder

[domenukk]

Alternatively we can just print the complete mutations tuple, and the id

[Jay-1409]

Alternatively we can just print the complete mutations tuple, and the id

Hey,
For the alternative, did you mean this?

                    .ok_or_else(|| {
                        Error::unknown(format!(
                            "Missing mutation name for id {}. Available mutations: {:?}",
                            idx.0,
                            self.scheduled.mutations().names()
                        ))
                    })?;