Fix build by making the registry guarded by an ArcMutex.

src/intermediate/footnote_definition.rs

@@ -1,7 +1,9 @@
 use super::macros::intermediate;
+use super::registry::register_footnote_definition;
 use super::registry::Registry;
 use super::IAstNode;
 use crate::error::CustomError;
+use crate::intermediate::RefRegistry;
 
 #[derive(Debug, Clone)]
 pub(crate) struct IFootnoteDefinition {}
@@ -12,9 +14,7 @@ intermediate!(
     original,
     registry,
     {
-        registry
-            .register_footnote_definition(original.label, &original.children)
-            .await?;
+        register_footnote_definition(registry, original.label, &original.children).await?;
         Ok(IFootnoteDefinition {})
     }
 );
@@ -26,8 +26,8 @@ pub(crate) struct IRealFootnoteDefinition {
 }
 
 impl IRealFootnoteDefinition {
-    pub(crate) async fn new<'reg, 'orig, 'parse>(
-        registry: &'reg mut Registry<'orig, 'parse>,
+    pub(crate) async fn new<'orig, 'parse>(
+        registry: RefRegistry<'orig, 'parse>,
         footnote_id: usize,
         contents: Vec<IAstNode>,
     ) -> Result<IRealFootnoteDefinition, CustomError> {