admins get misleading error message while creating a project when project limit is reached

Summary

I tried, as an Gitlab-Admin, to create a new Project within my namespace. Using /projects/new and selecting my username as namespace, i get the following error:

The form contains the following error:
Namespace is not valid

Creating Projects for other Namespaces does work as intended.

Steps to reproduce

• be admin
• have reached the number of projects
• go to /projects/new
• enter any project name
• choose your user namespace
• click create

What is the current bug behavior?

As Admin you get

The form contains the following error:
Namespace is not valid

when chosing your user namespace as target namespace for a new project

What is the expected correct behavior?

Getting a error message telling me that i have reached the project limit.

Relevant logs and/or screenshots

Environment

Gitlab Version: 12.3.5 (2417d5be)

Proposal

On the new project creation screen:

• Check for limit
• add warning banner:
  • Heading: New project creation has been disabled
  • You have reached the maximum limit of projects you can create. Please delete any projects you are not using or upgrade your GitLab subscription level.
• disable the relevant buttons
  • Remove link from card (along with hover state).
  • Use $gray-50 (#f0f0f0) for background.
  • Use $gray-500 (#666) for text.
• Resolve button behavior inconsistency (this could be a separate issue)

New project creation screen	Disabled state

Previous proposal

Valid state - able to create new projects	Project limit reached