Bug 2067107 - Check string allocation in ModuleLoader::CreateTextModule. r=dom-core-reviewers,jjaschke

Differential Revision: https://phabricator.services.mozilla.com/D325000

dom/script/ModuleLoader.cpp

@@ -592,7 +592,7 @@ nsresult ModuleLoader::CreateTextModule(
                                           aRequest->mLoadContext.get());
   NS_ENSURE_SUCCESS(rv, rv);
 
-  auto compile = [&](auto& source) {
+  auto compile = [&](auto& source) -> JSObject* {
     using T = decltype(source);
     static_assert(std::is_same_v<T, JS::SourceText<char16_t>&> ||
                   std::is_same_v<T, JS::SourceText<Utf8Unit>&>);
@@ -604,6 +604,9 @@ nsresult ModuleLoader::CreateTextModule(
     } else {
       str = JS_NewUCStringCopyN(aCx, source.get(), source.length());
     }
+    if (!str) {
+      return nullptr;
+    }
 
     JS::Rooted<JS::Value> defaultExport(aCx, JS::StringValue(str));
     return JS::CreateDefaultExportSyntheticModule(aCx, defaultExport);