Ipang I thought it might be something like that. Ryan Zico (Challenge Me) what version of the app do you have? Can you try it on a modern browser to see if you still get an error?
Anyway, line 12 is where the backticks start which as we know is ES6, but if Ryan changed var markup to const markup, then line 11 would've errored.
It's working for me. I just copied your code into a new code but just to double check.
Can you try this one to see if you're still getting an error in the console?