Ensure the callback is a function when executing JS

lib/browser/api/web-contents.js

@@ -115,8 +115,8 @@ const asyncWebFrameMethods = function (requestId, method, callback, ...args) {
     this.send('ELECTRON_INTERNAL_RENDERER_ASYNC_WEB_FRAME_METHOD', requestId, method, args)
     ipcMain.once(`ELECTRON_INTERNAL_BROWSER_ASYNC_WEB_FRAME_RESPONSE_${requestId}`, function (event, error, result) {
       if (error == null) {
-        if (callback != null) callback(result)
         resolve(result)
+        if (typeof callback === 'function') callback(result)
       } else {
         reject(error)
       }