Bug 1771858 - Handle interrupt in AsyncModuleExecutionFulfilled; r=jonco

In AsyncModuleExecutionFulfilled, it's possible that the call to GatherAsyncParentCompletions
will fail if we are interrupted. The current code assumes that this is only reachable as a
result of an OOM. This changes the assertion to an if statement to handle being interrupted.

Differential Revision: https://phabricator.services.mozilla.com/D147954

js/src/builtin/ModuleObject.cpp

@@ -2311,9 +2311,13 @@ void js::AsyncModuleExecutionFulfilled(JSContext* cx,
 
   Rooted<ModuleVector> sortedList(cx);
   if (!GatherAvailableModuleAncestors(cx, module, &sortedList)) {
-    // We have OOM'd -- all bets are off, reject the promise. Not much more we
-    // can do.
-    MOZ_ASSERT(cx->isExceptionPending());
+    // We have been interrupted or have OOM'd -- all bets are off, reject the
+    // promise. Not much more we can do.
+    if (!cx->isExceptionPending()) {
+      AsyncModuleExecutionRejected(cx, module, UndefinedHandleValue);
+      return;
+    }
+
     RootedValue exception(cx);
     if (!cx->getPendingException(&exception)) {
       return;