Add undefined check

Defensive programming per last sentence of paragraph 8 in web3#3573 (comment)
wbt · Jun 8, 2020 · a182d7a · a182d7a
1 parent 076fd46
commit a182d7a
Showing 1 changed file with 3 additions and 1 deletion.
diff --git a/packages/web3-providers-ws/src/index.js b/packages/web3-providers-ws/src/index.js
@@ -130,7 +130,9 @@ WebsocketProvider.prototype._onMessage = function (e) {
         }
 
         if (_this.responseQueue.has(id)) {
-            _this.responseQueue.get(id).callback(false, result);
+            if(_this.responseQueue.get(id).callback !== undefined) {
+                _this.responseQueue.get(id).callback(false, result);
+            }
             _this.responseQueue.delete(id);
         }
     });