fix(rspack_core): correct COW uniqueness check in dependency_by_id_mut to consider weak refs and improve panic message

Author: cursoragent

crates/rspack_core/src/module_graph/mod.rs

@@ -598,10 +598,13 @@ impl ModuleGraph {
       .dependencies
       .get_mut(dependency_id)
       .unwrap_or_else(|| panic!("Dependency with ID {dependency_id:?} not found"));
-    if Arc::strong_count(dep) != 1 {
+    // Ensure unique mutable access; account for both strong and weak refs.
+    if Arc::get_mut(dep).is_none() {
       *dep = Arc::from(clone_box(dep.as_ref()));
     }
-    Arc::get_mut(dep).unwrap_or_else(|| panic!("Dependency with ID {dependency_id:?} not found"))
+    Arc::get_mut(dep).unwrap_or_else(|| {
+      panic!("Cannot obtain unique mutable access for dependency with ID {dependency_id:?}")
+    })
   }
 
   /// Uniquely identify a module by its dependency