Misc fixes

[praschke]

format argument:

$ mons mods resolve main
error: An unhandled exception has occurred:
error:   KeyError('resolve_count')
error: Use the --debug flag to disable clean exception handling.

missing everest version:

$ mons mods resolve main
2 dependencies missing
error: Mod 'EverestCore' could not be resolved and is not a valid URL.
error: Mod 'EverestCore' could not be resolved and is not a valid URL.
error: Encountered an error while resolving mods.
error: Encountered an error while resolving mods.
Continue anyways? [y/N]: y
1 mod to install:
  WinterCollab2021Audio: 1.3.0
After this operation, an additional 154.5 MiB disk space will be used
Continue? [Y/n]: n
Aborted!

WinterCollab2021Audio will always be considered missing. everest.yaml:

- Name: WinterCollab2021Audio
  Version: 1.3.0
  Dependencies:
  - Name: Everest

with the fix:

$ mons mods resolve main
1 dependency missing
error: Mod 'EverestCore' could not be resolved and is not a valid URL.
error: Mod 'EverestCore' could not be resolved and is not a valid URL.
error: Encountered an error while resolving mods.
error: Encountered an error while resolving mods.
Aborted!