js-react template: output renderComp throws on null initial payload

Summary

The js-react shiny create template's example app raises a client-side error on first render:

Cannot destructure property 'value' of 'object null' as it is null

The error is thrown inside the template's own renderComp in shiny/templates/package/js-react/srcts/index.tsx:

makeReactOutput<{ value: string }>({
  name: "custom-component-output",
  selector: "custom-component-output",
  renderComp: ({ value }) => (   // ← destructures `value`, but the payload is `null`
    <div style={{ backgroundColor: value, ... }} />
  ),
});

When @posit-dev/shiny-bindings-react's renderValue(el, payload) is invoked with payload === null during the initial output lifecycle, the destructure of null throws.

Reproduction

shiny create --template js-react --package-name my_component --dir /tmp/my_component
cd /tmp/my_component
npm ci && npm run build
pip install -e . shiny
shiny run example-app/app.py
# open in browser → red error overlay / DevTools console shows the destructure error

Fix (probably template-side)

Either guard the renderComp:

renderComp: (data) => {
  if (!data) return null;
  return <div style={{ backgroundColor: data.value, ... }} />;
}

…or change @posit-dev/shiny-bindings-react to skip rendering when the payload is null.

Pre-existing, not a regression

Verified the bug is unrelated to #2237's lodash bump — it reproduces against both the original lodash 4.17.21 lockfile from main and the patched 4.18.1 lockfile in #2237. See #2237 for the testing setup that surfaced this.

Start with shiny/templates/package/js-react/srcts/index.tsx and reproduce the issue using the listed shiny create, npm, and shiny run commands. Check the initial render path where renderComp receives a null payload. Done means the generated example app opens without the destructuring error during its first render.