Issue Summary

This is reproducible on Data Center: (no)

Steps to Reproduce

I was able to reproduce the issue in my test Statuspage.
1. Create an incident
2. Try subscribing to the incident from the page viewer view
3. Leave the email input box empty and click on subscribe
4. The error message is shown with a green background:

5. When the user tries to subscribe to the entire page and leaves the email empty, they see the error with a red background as expected:

Expected Results

When the email input is left blank, the error should be shown with a red background.

Actual Results

The error is currently being shown with a green background (Which may indicate success)

Workaround

There is no known workaround for this at the moment