Merge pull request #1501 from 0xProject/fix/utils/promisify-not-accounting-for-undefined-error

[utils] account for undefined errors in promisify, not only null (and fix instant in Opera)

2 files changed, 10 insertions, 1 deletions

diff --git a/packages/utils/CHANGELOG.json b/packages/utils/CHANGELOG.json
index fb85c4174..d84e32dd2 100644
--- a/packages/utils/CHANGELOG.json
+++ b/packages/utils/CHANGELOG.json
@@ -1,5 +1,14 @@
 [
     {
+        "version": "3.0.0",
+        "changes": [
+            {
+                "note": "Make `promisify` resolve when the callback error is undefined.",
+                "pr": 1501
+            }
+        ]
+    },
+    {
         "version": "2.1.1",
         "changes": [
             {
diff --git a/packages/utils/src/promisify.ts b/packages/utils/src/promisify.ts
index 29d626b61..e82251a0f 100644
--- a/packages/utils/src/promisify.ts
+++ b/packages/utils/src/promisify.ts
@@ -10,7 +10,7 @@ export function promisify<T>(originalFn: (...args: any[]) => void, thisArg?: any
     const promisifiedFunction = async (...callArgs: any[]): Promise<T> => {
         return new Promise<T>((resolve, reject) => {
             const callback = (err: Error | null, data?: T) => {
-                _.isNull(err) ? resolve(data) : reject(err);
+                _.isNull(err) || _.isUndefined(err) ? resolve(data) : reject(err);
             };
             originalFn.apply(thisArg, [...callArgs, callback]);
         });