Not showing proper error message when failing create roles

Description

When creating a role using an existing role name, that cannot be done. And it's not showing any error message. Need to add a proper message when that happens.

Suggested Labels:

Optional comma-separated list of suggested labels. Non-committers can’t assign labels to issues, so this will help issue creators who are not a committer to suggest a possible label

Suggested Assignees:

Optional comma-separated list of suggested team members who should attend the issue. Non-committers can’t assign issues to assignees, so this will help issue creators who are not a committer to suggest possible assignees

Affected Product Version:

OS, DB, other environment details and versions:

Steps to reproduce:

Related Issues: