This fixes 46d9a09698. There was a reason why this was not implemented
as an assert-type error nor as a user-facing error: network problems
happen.
We cannot pop an error up every time:
* The computer is offline! 😱 GIMP is not made to be run as a connected
software and working on GIMP with a non-connected computer is a
perfectly valid way of using GIMP.
* gimp.org is down (it's rare, but it happens and it should not have any
impact to creators with GIMP).
* You are behind some kind of proxy or other complicated network
configuration which GIO is not able to pass through.
* And any other reason which could make your GIMP not able to read the
remote json file…
Instead let's check the more particular domain and error code, though
even this I hesitated between doing this change or simply reverting
commit 46d9a09698.
Indeed it's still quite a generic G_IO_ERROR_NOT_SUPPORTED error, so I
do hope we cannot get it in other normal conditions where reading a
remote link may fail. The last thing we want is GIMP popping up errors
which are neither bugs in our code, nor environment issues for which
anyone can do anything about.
eb0bfe7bdb