[gjs/ewlsh/fix-dynamic-module-resolution] Fix race condition in dynamic module resolution.

[Evan Welsh <ewlsh src gnome org>]

commit c443ffb1eca634ac996d2462ebbd06f618a2010b
Author: Evan Welsh <contact evanwelsh com>
Date:   Fri Jul 9 21:20:24 2021 -0700

    Fix race condition in dynamic module resolution.
    
    Previously the module could resolve while we were awaiting the source
    load and cause an import error.

 modules/internal/loader.js | 5 +++++
 1 file changed, 5 insertions(+)
---
diff --git a/modules/internal/loader.js b/modules/internal/loader.js
index 63a1c405..0d44f510 100644
--- a/modules/internal/loader.js
+++ b/modules/internal/loader.js
@@ -161,6 +161,11 @@ class ModuleLoader extends InternalModuleLoader {
             if (!result)
                 return null;
 
+            // Check if module loaded while awaiting.
+            module = registry.get(uri.uri);
+            if (module)
+                return module;
+
             const [text, internal = false] = result;
 
             const priv = new ModulePrivate(uri.uri, uri.uri, internal);