formatting of error text in web ui is not very noticeable

[alext-extracellular]

Hi there,
I was editing my DAGs and for a few minutes I did not know what was wrong, I thought the webui had crashed, but it was because I did not see the error message. Can I suggest some more obvious formatting, like red box, etc. to make it more obvious?

See image:

[yohamta]

Good point. Let's make it to be more noticeable. We would like to have an alert modal on save. Here's an example.