From 2219c1dd63e437c8c93fe0409641a4288ba7fb26 Mon Sep 17 00:00:00 2001
From: Lee Byron <lee@leebyron.com>
Date: Thu, 14 Nov 2019 10:36:07 -0800
Subject: [PATCH] [bug] Fix types for prime() to allow priming an Error (#217)

---
 README.md      | 1 +
 src/index.d.ts | 2 +-
 src/index.js   | 4 +++-
 3 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/README.md b/README.md
index 0dfbc16..369e6fa 100644
--- a/README.md
+++ b/README.md
@@ -344,6 +344,7 @@ Primes the cache with the provided key and value. If the key already exists, no
 change is made. (To forcefully prime the cache, clear the key first with
 `loader.clear(key).prime(key, value)`.) Returns itself for method chaining.
 
+To prime the cache with an error at a key, provide an Error instance.
 
 ## Using with GraphQL
 
diff --git a/src/index.d.ts b/src/index.d.ts
index 4bb5cf4..d693354 100644
--- a/src/index.d.ts
+++ b/src/index.d.ts
@@ -56,7 +56,7 @@ declare class DataLoader<K, V, C = K> {
    * Adds the provied key and value to the cache. If the key already exists, no
    * change is made. Returns itself for method chaining.
    */
-  prime(key: K, value: V): this;
+  prime(key: K, value: V | Error): this;
 }
 
 declare namespace DataLoader {
diff --git a/src/index.js b/src/index.js
index c12525f..f109d48 100644
--- a/src/index.js
+++ b/src/index.js
@@ -172,8 +172,10 @@ class DataLoader<K, V, C = K> {
   /**
    * Adds the provided key and value to the cache. If the key already
    * exists, no change is made. Returns itself for method chaining.
+   *
+   * To prime the cache with an error at a key, provide an Error instance.
    */
-  prime(key: K, value: V): this {
+  prime(key: K, value: V | Error): this {
     var cache = this._promiseCache;
     if (cache) {
       var cacheKey = getCacheKey(this._options, key);