Fix blank preview on no code demos

[sonnyp]

Fixes #812
Closes #820

@theCapypara thanks a lot for the bug report and PR
Took me a while to wrap my head around what was going on. This is the culprit

https://github.com/workbenchdev/Workbench/blob/58b40d9802d14cbcc613a4f25489858783b808b2/src/window.js#L268-L272C6

For that particular code path (javascript selected, demo without js) it wouldn't update the preview

One of the issue is that demos without code shouldn't have autorun: true. I will fix that.
But in any case - I don't want Workbench to misbehave even if the demo json is incorrect.

This is a slightly different approach to what you suggested that instead separates load and run in a way that load is always called before run.

[theCapypara]

Oh this is much better.
I was missing the insight into the inner workings of how it all works to properly do that, but I think separating them is exactly the way to go.

You may want to check if that cleanup I did for the console clearing is still necessary with this. When I did the original PR I noticed that compiler errors would immediately get cleared after refactoring, I'm not 100% sure this couldn't happen now as well, but I think it might.

[theCapypara]

also the CI failure is strange 🤔

[sonnyp]

I noticed that compiler errors would immediately get cleared after refactoring

I'm not following - but we can chat about it for clarification. I'll merge and we can address this separately if needed.