chore(shareReplay): ensure subscription is when source completes

src/internal/operators/shareReplay.ts

@@ -152,7 +152,6 @@ function shareReplayOperator<T>({
   let refCount = 0;
   let subscription: Subscription | undefined;
   let hasError = false;
-  let isComplete = false;
 
   return function shareReplayOperation(this: Subscriber<T>, source: Observable<T>) {
     refCount++;
@@ -168,19 +167,24 @@ function shareReplayOperator<T>({
           subject!.error(err);
         },
         complete() {
-          isComplete = true;
           subscription = undefined;
           subject!.complete();
         },
       });
+      // The following condition is needed because source can complete synchronously
+      // upon subscription. When that happens `subscription` is first set to `undefined`
+      // and right after is set to the "closed subscription" returned by `subscribe` 
+      if (subscription.closed && !hasError) {
+        subscription = undefined;
+      }
     } else {
       innerSub = subject.subscribe(this);
     }
 
     this.add(() => {
       refCount--;
       innerSub.unsubscribe();
-      if (subscription && !isComplete && useRefCount && refCount === 0) {
+      if (subscription && useRefCount && refCount === 0) {
         subscription.unsubscribe();
         subscription = undefined;
         subject = undefined;