[IMPROVE] Saving duplicate tag name, get message instead or page reload

[BobWritesCode]

What needs to be improved?
When you enter a tag that already exists, it does not save, and the page just reloads.

Why does it need to be improved?
Provide better user experience feedback

How should it be improved?
Instead of reloading the page, an error message to say that the tag already exists.

Provide any evidence such as screenshots / code:

[BobWritesCode]

The same improvement can be done when making no changes and just saving.

[BobWritesCode]

Same improvements can also be gone for game management.