Add checks for is_empty.

src/types/dynamic.rs

@@ -206,14 +206,10 @@ enum DynamicReadLockInner<'d, T: Clone> {
     /// A simple reference to a non-shared value.
     Reference(&'d T),
 
-    /// A read guard to a shared [`RefCell`][std::cell::RefCell].
+    /// A read guard to a shared value.
     #[cfg(not(feature = "no_closure"))]
     #[cfg(not(feature = "sync"))]
-    Guard(std::cell::Ref<'d, Dynamic>),
-    /// A read guard to a shared [`RwLock`][std::sync::RwLock].
-    #[cfg(not(feature = "no_closure"))]
-    #[cfg(feature = "sync")]
-    Guard(std::sync::RwLockReadGuard<'d, Dynamic>),
+    Guard(crate::func::native::LockGuard<'d, Dynamic>),
 }
 
 impl<'d, T: Any + Clone> Deref for DynamicReadLock<'d, T> {
@@ -245,7 +241,7 @@ enum DynamicWriteLockInner<'d, T: Clone> {
 
     /// A write guard to a shared value.
     #[cfg(not(feature = "no_closure"))]
-    Guard(crate::func::native::LockGuard<'d, Dynamic>),
+    Guard(crate::func::native::LockGuardMut<'d, Dynamic>),
 }
 
 impl<'d, T: Any + Clone> Deref for DynamicWriteLock<'d, T> {

src/types/interner.rs

@@ -59,7 +59,7 @@ impl StringsInterner {
             _ => unreachable!("unsupported prefix {}", prefix.as_ref()),
         };
 
-        if dict.contains_key(text.as_ref()) {
+        if !dict.is_empty() && dict.contains_key(text.as_ref()) {
             dict.get(text.as_ref()).unwrap().clone()
         } else {
             let value: ImmutableString = mapper(text.as_ref()).into();

src/types/scope.rs

@@ -516,7 +516,7 @@ impl Scope<'_> {
     #[inline]
     pub(crate) fn add_entry_alias(&mut self, index: usize, alias: Identifier) -> &mut Self {
         let aliases = self.aliases.get_mut(index).unwrap();
-        if !aliases.contains(&alias) {
+        if aliases.is_empty() || !aliases.contains(&alias) {
             aliases.push(alias);
         }
         self
@@ -533,7 +533,7 @@ impl Scope<'_> {
             .rev()
             .enumerate()
             .fold(Self::new(), |mut entries, (index, name)| {
-                if !entries.names.contains(name) {
+                if entries.names.is_empty() || !entries.names.contains(name) {
                     let orig_value = &self.values[len - 1 - index];
                     let alias = &self.aliases[len - 1 - index];
                     let mut value = orig_value.clone();