Standalone slingcode.html unable to launch apps

Hi, I'm unable to launch an app from slingcode if I download the slingcode.html file and run it locally. After clicking on the launch button for (for instance) Hello World, I just get a blank screen with no app. Running it from slingcode.net/slingcode.html works as expected. In addition, after I've opened the blank screen/no app, if I then edit the app, the stop button shows but doesn't seem to work
Tried on both Chrome and Brave.

The console for the app edit screen when clicking on the stop button gives the following output:
```
VM5 slingcode.html:1 Failed to execute 'postMessage' on 'DOMWindow': The target origin provided ('null') does not match the recipient window's origin ('null').
(anonymous) @ /C:/Users/mysti/OneDrive/Desktop/slingcode.html?app=c87e1e4a-f9f0-49e2-bcef-b3e7a2b1a8f9:1
Ig @ VM5 slingcode.html:1
c @ VM5 slingcode.html:1
t @ VM5 slingcode.html:1
(anonymous) @ VM5 slingcode.html:1
u @ VM5 slingcode.html:1
(anonymous) @ VM5 slingcode.html:1
r @ VM5 slingcode.html:1
J @ VM5 slingcode.html:1
K @ VM5 slingcode.html:1
ee @ VM5 slingcode.html:1
ae @ VM5 slingcode.html:1
Xr @ VM5 slingcode.html:1
m @ VM5 slingcode.html:1
be @ VM5 slingcode.html:1
ve @ VM5 slingcode.html:1
l.unstable_runWithPriority @ VM5 slingcode.html:1
Ct @ VM5 slingcode.html:1
h @ VM5 slingcode.html:1
(anonymous) @ VM5 slingcode.html:1
/C:/Users/mysti/OneDrive/Desktop/slingcode.html?app=c87e1e4a-f9f0-49e2-bcef-b3e7a2b1a8f9:1 Failed to execute 'postMessage' on 'DOMWindow': The target origin provided ('null') does not match the recipient window's origin ('null').
```

The console for the blank screen gives the following output:
```
Invalid asm.js: Expected function name
slingcode.html?app=c87e1e4a-f9f0-49e2-bcef-b3e7a2b1a8f9:1 CodeMirror includes: {} {} {} {}
slingcode.html?app=c87e1e4a-f9f0-49e2-bcef-b3e7a2b1a8f9:1 can-make-files? true
slingcode.html?app=c87e1e4a-f9f0-49e2-bcef-b3e7a2b1a8f9:1 can-p2p? true
slingcode.html?app=c87e1e4a-f9f0-49e2-bcef-b3e7a2b1a8f9:1 main!
slingcode.html?app=c87e1e4a-f9f0-49e2-bcef-b3e7a2b1a8f9:1 reload!
```

Happy to help however I can!