JSON.stringify cannot render preloaded object

[tve]

Build environment: Linux
Moddable SDK version: 3.9.2
Target device: Moddable Two

Description
Trying to JSON.stringify a preloaded object throws an exception:

var test = { x: 1, y: 2 }
trace(`test: ${JSON.stringify(test)}\n`)

export default function() {
    trace(`test: ${JSON.stringify(test)}\n`)
}

The manifest contains "preload": "main".
The first trace is printed at compile time as expected.
The second fails with "stringify: read only value!".

Expected behavior
I expected JSON.stringify to succeed.

[phoddie]

Yes, this has been reported before (see #340). There's no immediate intention to address it. A workaround is to use structuredClone.

[tve]

thanks, my searches didn't show this one...
two suggestions: document it (e.g. in the XS preload doc in the section on what can't be preloaded) and detect it in JSON;.stringify and produce a more explicit error and perhaps even suggest structuredClone

[phoddie]

I've updated the doc. Thank you for the suggestion.

Adding documentation into the runtime is a slippery slope, and not great for a runtime targeting extremely resource constrained targets.