From 3c5233297a20b68d87f6ae5aa541e61783067fed Mon Sep 17 00:00:00 2001
From: Henrik Giesel <hengiesel@gmail.com>
Date: Mon, 22 Mar 2021 02:58:19 +0100
Subject: [PATCH] Avoid duplicate initial fetching with asyncReactive

---
 ts/graphs/asyncReactive.ts | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/ts/graphs/asyncReactive.ts b/ts/graphs/asyncReactive.ts
index d07b71749..394acc3a7 100644
--- a/ts/graphs/asyncReactive.ts
+++ b/ts/graphs/asyncReactive.ts
@@ -13,14 +13,15 @@ function useAsyncReactive<T, E>(
 ): AsyncReativeData<T, E> {
     const promise = derived(
         dependencies,
-        (_, set) => set(asyncFunction()),
-        asyncFunction()
+        (_, set: (value: Promise<T> | null) => void) => set(asyncFunction()),
+        // initialize with null to avoid duplicate fetch on init
+        null
     );
 
     const value = derived(
         promise,
         ($promise, set: (value: T) => void) => {
-            $promise.then((value: T) => set(value));
+            $promise?.then((value: T) => set(value));
         },
         null
     );
@@ -28,7 +29,7 @@ function useAsyncReactive<T, E>(
     const error = derived(
         promise,
         ($promise, set: (error: E | null) => void) => {
-            $promise.catch((error: E) => set(error));
+            $promise?.catch((error: E) => set(error));
             return () => set(null);
         },
         null