apply suggestion

Author: JonasDov

packages/itwin/tree-widget/src/tree-widget-react/components/trees/common/internal/caches/AlwaysAndNeverDrawnElementInfoCache.ts

@@ -252,8 +252,7 @@ export class AlwaysAndNeverDrawnElementInfoCache implements Disposable {
       latestCacheEntry.invalidateValue.next();
     }
     const set = setType === "always" ? this.#viewport.alwaysDrawn : this.#viewport.neverDrawn;
-    const setWithoutTransientElements = set ? [...set].filter((id) => !Id64.isTransient(id)) : undefined;
-    const queryObservable = this.queryAlwaysOrNeverDrawnElementInfo(setWithoutTransientElements, setType).pipe(
+    const queryObservable = this.queryAlwaysOrNeverDrawnElementInfo(set, setType).pipe(
       takeUntil(latestCacheEntry.invalidateValue),
       takeUntil(this.#disposeSubject),
       shareReplay(),
@@ -269,16 +268,20 @@ export class AlwaysAndNeverDrawnElementInfoCache implements Disposable {
     this.#disposeSubject.next();
   }
 
-  private queryAlwaysOrNeverDrawnElementInfo(setWithoutTransientElements: Array<ElementId> | undefined, setType: SetType): Observable<CachedNodesMap> {
-    const elementInfo = setWithoutTransientElements?.length
-      ? setWithoutTransientElements.length > ALWAYS_NEVER_BUFFER_THRESHOLD
+  private queryAlwaysOrNeverDrawnElementInfo(set: ReadonlySet<Id64String> | undefined, setType: SetType): Observable<CachedNodesMap> {
+    const elementInfo = set?.size
+      ? set.size > ALWAYS_NEVER_BUFFER_THRESHOLD
         ? // When set is larger, buffer helps to not block main thread for long periods of time
-          from(setWithoutTransientElements).pipe(
-            bufferCount(getOptimalBatchSize({ totalSize: setWithoutTransientElements.length, maximumBatchSize: ALWAYS_NEVER_BUFFER_THRESHOLD })),
+          from(set).pipe(
+            filter((id) => !Id64.isTransient(id)),
+            bufferCount(getOptimalBatchSize({ totalSize: set.size, maximumBatchSize: ALWAYS_NEVER_BUFFER_THRESHOLD })),
             releaseMainThreadOnItemsCount(2),
             mergeMap((block, index) => this.queryElementInfo(block, `${setType}-${index}`), 2),
           )
-        : this.queryElementInfo(setWithoutTransientElements, `${setType}-0`)
+        : this.queryElementInfo(
+            [...set].filter((id) => !Id64.isTransient(id)),
+            `${setType}-0`,
+          )
       : EMPTY;
     return elementInfo.pipe(
       releaseMainThreadOnItemsCount(500),
@@ -313,6 +316,9 @@ export class AlwaysAndNeverDrawnElementInfoCache implements Disposable {
     categoryElementPath: Id64Array;
   }> {
     return defer(() => {
+      if (elementIds.length === 0) {
+        return EMPTY;
+      }
       const executor = createECSqlQueryExecutor(this.#viewport.iModel);
       return executor.createQueryReader(
         {