bug#25719: "guix package -i" exception should be a normal error message

[zimoun]

Hi Danny
On Wed, 02 Dec 2020 at 14:35, Danny Milosavljevic <dannym@scratchpost.org> 
wrote:

>> > substitute: 1727: 3 [%start-stack load-stack #<procedure a97d60 at 
>> > ice-9/boot-9.scm:4047:10 ()>]
>> > substitute: 1732: 2 [#<procedure a99b70 ()>]
>> > substitute: In unknown file:
>> > substitute:    ?: 1 [primitive-load 
>> > "/gnu/store/175nlv448nk5kagwwl3zyy2w4726qfz6-guix-0.12.0-4.d9da/bin/.guix-real"]
>> > substitute: In guix/ui.scm:
>> > substitute: 1228: 0 [run-guix-command substitute "--query"]
>> > substitute: 
>> > substitute: guix/ui.scm:1228:8: In procedure run-guix-command:
>> > substitute: guix/ui.scm:1228:8: Throw to key `bad-response' with args 
>> > `("Bad Response-Line: ~s" (""))'.
>> >
>> > It might make sense to
>> >
>> > (a) convert that into a normal runtime error message and  
>> 
>> What do you mean?
>
> The above is an exception.
>
> In this case the download failed--and unfortunately that is a completely 
> normal
> thing on the internet.  Therefore, that is not something you'd use an 
> exception
> for.
>
> There is no added information that could help the user in the exception.
> For example it doesn't list the URL--the one thing that would actually help.

If I understand correctly, instead of the backtrace you would like a
message captured by the exception, right?

All the best,
simon