Improve error message when attempting to refreseh a local snap

[sed-i]

What needs to get done

I have a snap installed from a local file

$ which obsidian
/snap/bin/obsidian

Now I see it in the store

$ snap info obsidian
name:      obsidian
summary:   Obsidian
publisher: –
store-url: https://snapcraft.io/obsidian
license:   unset
description: |
  Obsidian
commands:
  - obsidian
refresh-date: 2022-08-02
channels:
  latest/stable:    1.3.5  2023-06-01 (12) 113MB classic
  latest/candidate: ↑                            
  latest/beta:      ↑                            
  latest/edge:      ↑                            
installed:          0.15.9            (x1)  77MB -

But if I try to refresh it I get an obscure error message:

$ sudo snap refresh obsidian
error: local snap "obsidian" is unknown to the store, use --amend to proceed anyway

I happen to remember I installed it from file, but the error message could be more informative.

Why it needs to get done

Reduce user confusion around refreshing snaps.

[lengau]

Hi! This looks like something you'd need to ask the snapd team about. I've copied this bug report over to Launchpad and subscribed you to it.