feat(replyform): Avoid flash of enabled Post button

[ConradJChan]

https://formik.org/docs/api/withFormik#mappropstoerrors-props-props--formikerrorsvalues

Adding the mapPropsToErrors with an initial error allows the Post button to render disabled on the initial mount before the formik validate method kicks in.

[mingzexiao6]

Is there any way to add a test for the change?

[ConradJChan]

Yes? I tried but it also ends up throwing a console error because validateOnMount: true causes a re-render and results in
console.error node_modules/react-dom/cjs/react-dom.development.js:88 Warning: An update to Formik inside a test was not wrapped in act(...). When testing, code that causes React state updates should be wrapped into act(...):

Which is not great. It's a simple change, I'm thinking we skip the test