How to change invalid or error occurred?

[GeneticAlpha]

So the pages that state an error has occurred and invalid exemption etc, is there a way I can change those to titles of that specific page?

For example, in inventory, it says:

Invalid ID Specified
You currently do not have any items in inventory.

and I would like that Invalid ID Specified to be using the title of the page instead, so:

Inventory Empty
you currently do not have any items in inventory.

Different pages have the invalids and errors, so I'm just wanting to set titles to these pages. Can anyone help?