Error messages vs pages

Hello. My team and I are new to using Auth0. We’re planning on implementing the New Universal Login using liquid templates. We’re confused about when we will be redirected to a custom error page versus when the error will appear within the universal login.

I see this documentation about custom error pages, which suggests to me that all errors will be redirected to the callback url…probably with an error from this list of common authentication errors.

However when I look at the documentation around customizing the new universal login, I see that we have keys available to us like “custom-script-error-code”, “no-username”, and “invalid-email-format”.

We would prefer to have the New Universal Login handle all the errors/scenarios listed in “Customize New Universal Login Pages”. Our designer sent over an image they found that demonstrates what we think the experience will be.

However, when should we expect the error message within the login widget versus users being redirected to a custom error page?

Thank you!