[oden-js] Fix various bugs in module loader

oden-js/src/runtime.rs

@@ -3,10 +3,11 @@ use crate::ContextRef;
 use oden_js_sys as sys;
 use std::cell::RefCell;
 use std::ffi::CStr;
+use std::sync::Arc;
 
 struct PrivateState {
     refs: u64,
-    loader: Box<dyn ModuleLoader>,
+    loader: Arc<Box<dyn ModuleLoader>>,
 }
 
 impl PrivateState {
@@ -20,9 +21,16 @@ impl PrivateState {
             Err(_) => return std::ptr::null_mut(),
         };
 
-        let state = opaque as *mut PrivateState;
+        let loader = unsafe {
+            let ptr = opaque as *const RefCell<PrivateState>;
+            ptr.as_ref()
+                .expect("We already know this runtime is one of ours!")
+                .borrow()
+                .loader
+                .clone()
+        };
         let context = ContextRef::from_raw(ctx);
-        load_module(&context, path, &mut (*state).loader)
+        load_module(&context, path, &loader)
     }
 }
 
@@ -39,7 +47,7 @@ impl Runtime {
     pub fn with_loader<TLoader: ModuleLoader + 'static>(loader: TLoader) -> Runtime {
         let state = Box::new(RefCell::new(PrivateState {
             refs: 1,
-            loader: Box::new(loader),
+            loader: Arc::new(Box::new(loader)),
         }));
         let rt = unsafe {
             let rt = sys::JS_NewRuntime();