make retract_local_clauses safe, remove warning about overwriting warning in do_not_duplicate_path_components test

src/machine/load_state.rs

@@ -344,7 +344,7 @@ impl<'a> LoadState<'a> {
         key: PredicateKey,
         clause_locs: &SliceDeque<usize>,
     ) {
-        let (clause_target_poses, is_dynamic) = self
+        let result_opt = self
             .wam
             .indices
             .get_predicate_skeleton(&compilation_target, &key)
@@ -358,8 +358,9 @@ impl<'a> LoadState<'a> {
                     })
                     .collect(),
                  skeleton.is_dynamic)
-            }).unwrap();
+            });
 
+        if let Some((clause_target_poses, is_dynamic)) = result_opt {
             self.retract_local_clauses_by_locs(
                 compilation_target,
                 key,
@@ -367,6 +368,7 @@ impl<'a> LoadState<'a> {
                 is_dynamic,
             );
         }
+    }
 
     pub(super) fn retract_local_clauses_by_locs(
         &mut self,

tests/scryer/issues.rs

@@ -29,7 +29,6 @@ fn do_not_duplicate_path_components() {
         "\
         caught: e\n\
         false.\n\
-        Warning: overwriting $initialization_goals/1\n\
         caught: e\n\
         false.\n\
         ",