Fix AsyncCollection.filter to allow for async filter functions

src/util/collection/AsyncCollection.ts

@@ -401,7 +401,17 @@ export class AsyncCollection<T> {
         let newItems: CollectionItem<T>[] = []
 
         await this.inChunks(async items => {
-            newItems = newItems.concat(items.filter(func).all())
+            const filterItems: CollectionItem<T>[] = []
+
+            for ( let i = 0; i < items.length; i += 1 ) {
+                // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+                const item = items.get(i)!
+                if ( await func(item, i) ) {
+                    filterItems.push(item)
+                }
+            }
+
+            newItems = newItems.concat(filterItems)
         })
 
         return new Collection<T>(newItems)