Computed properties break _rerender

[aphitiel]

When a component uses computed properties, _rerender tries to set() those, which makes _checkReadOnly inside the component throw. This leads to a full reload when using svelte-loader with hotReload.

I couldn't find way to tell if a property is computed, though a possible workaround seems to be replacing this line with

  this.proxyTarget._updatingReadonlyProperty = true;
  this.set(oldstate);
  this.proxyTarget._updatingReadonlyProperty = false;

Although that feels somewhat dirty. What do you think?

[ekhaled]

cc. @Rich-Harris
I don't know if I remember right, but I seem to remember a fix in svelte where trying to set a computed prop would result in a no-op.

Maybe Rich can enlighten us... I'm on mobile now, but I'll try to find it later on

[ekhaled]

Hmm, I was mistakenly thinking about this sveltejs/svelte#893

Seems like throwing an error is the dev mode behaviour.

Where did you get the _updatingReadonlyProperty from? Is that something internal to svelte?

[aphitiel]

Thank for looking into it. Yup, it's here

[ekhaled]

@aphitiel just had a chat with @Rich-Harris and he says what you suggest won't break anything. So feel free to open a PR.

Or just let me know if you are busy and I will sort it out.

Thanks for the investigative debugging session 😀

[ekhaled]

closed in #7