Improve error message when a package already exists

[bortzmeyer]

Trying to hex publish a package when there is already one with this same name prints:

Publishing failed
account not authorized for this action

The error message is misleading, it has nothing to do with the account you use. Something like "package with the name foobar already exists" would be more sensible, IMHO.

[Coreastreet]

Hi bortzmeyer,

I wrote a basic fix. Hope it may be useful to future users.

Regards, Coreastreet

[Coreastreet]

[Coreastreet]

The picture illustrates the new error response.