We should fix all of our error messaging to users #7785
Description
This involves going through the whole app and figuring out where error messages come from and replacing them with strings we can translate. Currently, some (many?) error dialogs take the error from the server and shove it in front of the user, which isn't great. In the same branches, the dialogs can also show errors generated within the app which are translated.
This is to finally stop having "CORS request rejected" and to have a 100% translation on all possible strings in the app.