Better error message instead of "No entries in corpus"

libafl/src/schedulers/mod.rs

@@ -300,7 +300,7 @@ where
     /// Gets the next entry at random
     fn next(&mut self, state: &mut Self::State) -> Result<CorpusId, Error> {
         if state.corpus().count() == 0 {
-            Err(Error::empty("No entries in corpus".to_owned()))
+            Err(Error::empty("No entries in corpus. This often implies the target is not properly instrumented.".to_owned()))
         } else {
             let id = random_corpus_id!(state.corpus(), state.rand_mut());
             self.set_current_scheduled(state, Some(id))?;

libafl/src/schedulers/powersched.rs

@@ -259,7 +259,7 @@ where
 
     fn next(&mut self, state: &mut Self::State) -> Result<CorpusId, Error> {
         if state.corpus().count() == 0 {
-            Err(Error::empty(String::from("No entries in corpus")))
+            Err(Error::empty(String::from("No entries in corpus. This often implies the target is not properly instrumented.")))
         } else {
             let id = match state.corpus().current() {
                 Some(cur) => {

libafl/src/schedulers/probabilistic_sampling.rs

@@ -158,7 +158,7 @@ where
     #[allow(clippy::cast_precision_loss)]
     fn next(&mut self, state: &mut Self::State) -> Result<CorpusId, Error> {
         if state.corpus().count() == 0 {
-            Err(Error::empty(String::from("No entries in corpus")))
+            Err(Error::empty(String::from("No entries in corpus. This often implies the target is not properly instrumented.")))
         } else {
             let rand_prob: f64 = (state.rand_mut().below(100) as f64) / 100.0;
             let meta = state.metadata_map().get::<ProbabilityMetadata>().unwrap();

libafl/src/schedulers/queue.rs

@@ -44,7 +44,7 @@ where
     /// Gets the next entry in the queue
     fn next(&mut self, state: &mut Self::State) -> Result<CorpusId, Error> {
         if state.corpus().count() == 0 {
-            Err(Error::empty("No entries in corpus".to_owned()))
+            Err(Error::empty("No entries in corpus. This often implies the target is not properly instrumented.".to_owned()))
         } else {
             let id = state
                 .corpus()

libafl/src/schedulers/tuneable.rs

@@ -119,7 +119,7 @@ where
     /// Gets the next entry in the queue
     fn next(&mut self, state: &mut Self::State) -> Result<CorpusId, Error> {
         if state.corpus().count() == 0 {
-            return Err(Error::empty("No entries in corpus".to_owned()));
+            return Err(Error::empty("No entries in corpus. This often implies the target is not properly instrumented.".to_owned()));
         }
         let id = if let Some(next) = Self::get_next(state) {
             // next was set

libafl/src/schedulers/weighted.rs

@@ -303,7 +303,7 @@ where
     fn next(&mut self, state: &mut S) -> Result<CorpusId, Error> {
         let corpus_counts = state.corpus().count();
         if corpus_counts == 0 {
-            Err(Error::empty(String::from("No entries in corpus")))
+            Err(Error::empty(String::from("No entries in corpus. This often implies the target is not properly instrumented.")))
         } else {
             let s = random_corpus_id!(state.corpus(), state.rand_mut());